Outdoor onsen at Nakanoshima in Nachikatsuura, Wakayama
A video showcasing the stool and shower used for cleaning off, an inside pool and an outside pool

In Japan, onsen (温泉) are hot springs and the bathing facilities and traditional inns around them. There are approximately 25,000 hot spring sources throughout Japan, and approximately 3,000 onsen establishments use naturally hot water from these geothermally heated springs.[1]

Onsen may be either outdoor baths (露天風呂 or 野天風呂, roten-buro / noten-buro) or indoor baths (内湯, uchiyu). Traditionally, onsen were located outdoors, although many inns have now built indoor bathing facilities as well. Nowadays, as most households have their baths, the number of traditional public baths has decreased,[2] but the popularity of sightseeing hot spring towns has increased.[3][better source needed] Baths may be either publicly run by a municipality or privately, often connecting to a lodging establishment such as a hotel, ryokan, or minshuku.

Indoor onsen at Asamushi Onsen

The presence of an onsen is often indicated on signs and maps by the symbol ♨, the kanji (yu, meaning "hot water"), or the simpler phonetic hiragana character ゆ (yu).



According to the Japanese Hot Springs Act (温泉法, Onsen Hō), onsen is defined as "hot water, mineral water, and water vapor or other gas (excluding natural gas of which the principal component is hydrocarbon) gushing from underground".[4] The law states that mineralized hot spring water that feeds an onsen must be at least 24 °C (75 °F) originating at a depth of at least 1.5 kilometres (0.93 mi), and contain specified amounts of minerals such as sulphur, sodium, iron, or magnesium.[1]

When onsen water contains distinctive minerals or chemicals, establishments often display what type of water it is,[5] in part because the specific minerals found in the water have been thought to provide health benefits.[6] Types include sulfur onsen (硫黄泉, iō-sen), sodium chloride onsen (ナトリウム泉, natoriumu-sen), hydrogen carbonate onsen (炭酸泉, tansan-sen), and iron onsen (鉄泉, tetsu-sen).

Mixed bathing

Guidebook to Hakone from 1811

Traditionally, men and women bathed together at both onsen and sentō communal bathhouses, but gender separation has been enforced at most institutions since the opening of Japan to the West during the Meiji Restoration.

Mixed bathing (混浴, kon'yoku) is currently banned in Japanese public baths.[7][8][a][10] Depending on the prefecture and local ordinances, children seven years old and younger may be exempt from this ban.[7]

Private onsen called "family baths" (家族風呂, kazokuburo) can be found in many locations throughout Japan. These can be reserved and used for mixed bathing.[11]



Ensuring cleanliness


As at a sentō at an onsen, all guests are expected to wash and rinse themselves thoroughly before entering the hot water. Bathing stations are equipped with stools, faucets, wooden buckets, and toiletries such as soap and shampoo; nearly all onsen also provide removable shower heads for bathing convenience. Entering the onsen while still dirty or with traces of soap on the body is socially unacceptable.[b]



Guests are not allowed to wear swimsuits in the baths and must be completely nude. However, there are some onsen that allow both men and women to enter together but require swimsuits. Many of these mixed onsen resemble more of a pool or waterpark than the traditional idea of an onsen.[12][13][14] In 2016, The Japan Times reported that guests were not normally allowed to wear swimsuits in the baths. However, some modern onsen required their guests to wear a swimming suit in their mixed baths.[15]



Onsen guests generally bring a small towel with them to use as a wash cloth. The towel can also provide a modicum of modesty when walking between the washing area and the baths. Some onsen allow one to wear the towel into the baths, while others have posted signs prohibiting this, saying that it makes it harder to clean the bath. It is against the rules to immerse or dip towels in the onsen bath water, since this can be considered unclean. People normally set their towels off to the side of the water when enjoying the baths, or place their folded towels on top of their heads.



By 2015, around half (56%) of onsen operators had banned bathers with tattoos from using their facilities.[16][17][18] The original reason for the tattoo ban was to keep out yakuza and members of other crime gangs who traditionally have elaborate full-body decoration.[19]

However, tattoo-friendly onsen do exist.[20] A 2015 study by the Japan National Tourism Organisation found that more than 30% of onsen operators at hotels and inns across the country will not turn someone with a tattoo away; another 13% said they would grant access to a tattooed guest under certain conditions, such as having the tattoo covered up.[16] Some towns have many tattoo-friendly onsen that do not require guests to cover them up. Two such towns are Kinosaki Onsen in Hyōgo and Beppu Onsen in Ōita.[21]

With the increase in foreign customers due to growing tourism, some onsen that previously banned tattoos are loosening their rules to allow guests with small tattoos to enter, provided they cover their tattoos with a patch or sticking plaster.[16][22]



Article 18, paragraph 1 of the Japanese Hot Springs Act publishes guidance on contraindications and cautions for bathing in hot springs, and drinking their respective waters.[23] Although millions of Japanese bathe in onsen every year with few noticeable side effects, there are still potential side effects to onsen usage, such as aggravating high blood pressure or heart disease.[24]

Legionella bacteria have been found in some onsen with poor sanitation.[25][26] For example, 295 people were infected with Legionella and seven died at an onsen in Miyazaki Prefecture in 2002.[26][27][c] Revelations of poor sanitary practices at some onsen have led to improved regulation by hot-spring communities to maintain their reputation.[28]

There have been reports of infectious disease found in hot bodies of water worldwide, such as various Naegleria species.[29] While studies have found the presence of Naegleria in hot spring waters, Naegleria fowleri, responsible for numerous fatal cases of primary amoebic meningoencephalitis around the world, has not been found to be present in the water at onsen.[29] Nevertheless, fewer than five cases have been seen historically in Japan, although not conclusively linked to onsen exposure.[30]

Many onsen display notices reminding anyone with open cuts, sores, or lesions not to bathe. Additionally, in recent years onsen are increasingly adding chlorine to their waters to prevent infection, although many onsen purists seek natural, unchlorinated onsen that do not recycle their water but instead clean the baths daily.[28] These precautions as well as proper onsen usage (i.e. not placing the head underwater, washing thoroughly before entering the bath) greatly reduce any overall risk to bathers.

Voyeurism is reported at some onsen. In 2016, The Japan Times reported that this was mitigated in some prefectures of Japan where nude mixed bathing is not permitted, and that visitors must wear swimsuits.[15][31][32] In 2021, several people were arrested in connection with an organized group accused of taking photos of women in open-air baths.[33][34]

Selected onsen

This section may contain unverified or indiscriminate information in embedded lists. Please help clean up the lists by removing items or incorporating them into the text of the article. (February 2019)
Old Tsuru-no-yu Bathhouse in Nyūtō Onsen area, Akita
Winter bathing at Tsuru-no-yu rotten-buro in Nyūtō, Akita
Kurokawa Onsen roten-buro in Kyushu
Japanese macaques enjoying a roten-buro open-air onsen at Jigokudani Monkey Park
Yumura-onsen's hot-spring resort and forests in Shin'onsen, Hyōgo
Dōgo Onsen hot springs (main building) in Matsuyama, Ehime
Ginzan Onsen in Obanazawa, Yamagata
Kusatsu Onsen
Onsen tamago (black egg) Miyanoshita Onsen

See also



  1. ^ due to varying interpretations of terminology and local ordinances, rare instances of mixed bathing still exist at places like Tsurunoyu Onsen where the water is opaque.[9]
  2. ^ In very isolated onsen, where there is no possibility to use soap before entering in the bath, onsen users are expected to at least rinse their body with the water of the bath before entering it.
  3. ^ In addition to this case, two people were infected and one died at Arima Onsen in 2022. In the same year, Legionella bacteria up to 3,700 times the standard value were detected at an onsen in Fukuoka Prefecture because the water was changed only twice a year.[27]


  1. ^ a b Erikson, August; Masui, Anette (2014). Sacred Waters: A Guide to Japanese Hot Springs. Karlstad, Sweden: Votum Forlag AB. p. 88. ISBN 978-91-87283-33-8.
  2. ^ "Public Baths in Japan". www.japan-guide.com. Retrieved 17 October 2018.
  3. ^ "[2018 Edition] 7 Select Onsen Hot Spring Areas Rising in Popularity among Foreign Tourists in Japan". WOW! JAPAN. Retrieved 17 October 2018.
  4. ^ "Hot Spring Act" (PDF). Ministry of the Environment Government of Japan. Retrieved 18 October 2020.
  5. ^ Serbulea, Mihaela; Payyappallimana, Unnikrishnan (2012). "Onsen (hot springs) in Japan—Transforming terrain into healing landscapes". Health & Place. 18 (6): 1366–73. doi:10.1016/j.healthplace.2012.06.020. PMID 22878276.
  6. ^ Tadanori, Matsuda (30 March 2015). "Soaking up the Benefits: Japan's Hot Springs Tradition". Nippon: Your doorway to Japan. Retrieved 27 August 2020.
  7. ^ a b 厚生労働省「公衆浴場における衛生管理理要領等の改正について〔公衆浴場法〕」(生食発1210第1号)(Retrieved June 3 2024) https://www.mhlw.go.jp/web/t_doc?dataId=00tc5492&dataType=1&pageNo=1
  8. ^ "サウナの男女混浴は法律でどうなってる?公衆浴場法・条例を調べてみた" retrieved June 3 2024
  9. ^ "Tsurunoyu Onsen" Retrieved June 3 2024
  10. ^ 「混浴ダメ!」何歳から? 10歳→7歳、国が通知 西日本新聞 Retrieved June 3 2024
  11. ^ "日帰り家族風呂を満喫するなら!知っておくべき混浴に関する条例" Retrieved June 3 2024
  12. ^ "温水プールが楽しい!西日本の温泉・お風呂テーマパーク15選" Retrieved June 4 2024
  13. ^ "5 Swimwear-allowed Onsen Spots near Tokyo" JW Web Magazine Retrieved June 4 2024
  14. ^ "Yunessun" Retrieved June 4 2024
  15. ^ a b Hadfield, James (10 December 2016). "Last splash: Immodest Japanese tradition of mixed bathing may be on the verge of extinction". The Japan Times. Retrieved 6 December 2018.
  16. ^ a b c Ryall, Julian (6 November 2015). "Japanese owners of famous 'onsen' hot springs soften their stance on tattoo ban to appease foreign visitors". Archived from the original on 17 January 2016.
  17. ^ Thompson, Ashley (6 November 2012). "If you need to bring drugs to Japan, sort out the paperwork — or else". The Japan Times. Archived from the original on 19 July 2015.
  18. ^ Xeni Jardin (22 December 2009). "Tattoo in Japan". Boing Boing. Archived from the original on 24 December 2009.
  19. ^ Onsen Warnings and Hassles, July 2019, retrieved 30 September 2020
  20. ^ Thompson, Ashley (27 November 2012). "Ink doesn't always cause a stink at the onsen". The Japan Times. Archived from the original on 19 July 2015.
  21. ^ "30 Tattoo Friendly Onsen in Japan".
  22. ^ Lund, Evie (17 April 2015). "Onsen in Nagano will now welcome foreigners with tattoos, as long as they patch 'em up". Archived from the original on 14 December 2015.
  23. ^ "The Criteria for the Notification, etc. on Contraindications and Cautions for Bathing and Drinking as specified in Article 18, Paragraph 1 of the Hot Springs Act" (PDF). Ministry of the Environment: Government of Japan. Retrieved 28 October 2022.
  24. ^ "Hot Spring Treatment|Hot Spring Encyclopedia|ONSEN|BEPPU CITY|". City.beppu.oita.jp. Retrieved 7 December 2010.
  25. ^ H. Miyamoto; S. Jitsurong; R. Shiota; K. Maruta; S. Yoshida; E. Yabuuchi (1997). "Molecular determination of infection source of a sporadic Legionella pneumonia case associated with a hot spring bath". Microbiol. Immunol. 41 (3): 197–202. doi:10.1111/j.1348-0421.1997.tb01190.x. PMID 9130230. S2CID 25016946.
  26. ^ a b Eiko Yabuuchi; Kunio Agata (2004). "An outbreak of legionellosis in a new facility of hot spring Bath in Hiuga City". Kansenshogaku Zasshi. 78 (2): 90–98. doi:10.11150/kansenshogakuzasshi1970.78.90. ISSN 0387-5911. PMID 15103899.
  27. ^ a b "「怖い菌ではないと思っていた」と運営会社社長。過去には7名死亡した事例も" (in Japanese). Shueisha. Retrieved 4 March 2023.
  28. ^ a b "Onsen: know what you're getting into". The Japan Times.
  29. ^ a b Shinji Izumiyama; Kenji Yagita; Reiko Furushima-Shimogawara; Tokiko Asakura; Tatsuya Karasudani; Takuro Endō (July 2003). "Occurrence and Distribution of Naegleria Species in Thermal Waters in Japan". The Journal of Eukaryotic Microbiology. 50 (s1): 514–5. doi:10.1111/j.1550-7408.2003.tb00614.x. PMID 14736147. S2CID 45052636.
  30. ^ Yasuo Sugita; Teruhiko Fujii; Itsurou Hayashi; Takachika Aoki; Toshirō Yokoyama; Minoru Morimatsu; Toshihide Fukuma; Yoshiaki Takamiya (May 1999). "Primary amebic meningoencephalitis due to Naegleria fowleri: An autopsy case in Japan". Pathology International. 49 (5): 468–70. doi:10.1046/j.1440-1827.1999.00893.x. PMID 10417693. S2CID 21576553.
  31. ^ "盗撮の実態、知っていますか? 10年で倍増/常習化しやすく 被害に遭わないためには…【NEXT特捜隊】". Shizuoka Shimbun (in Japanese). 21 November 2021. Retrieved 28 October 2022.
  32. ^ "<盗撮の闇(3)>奪われた日常 被害者、映像流出におびえ". 佐賀新聞 (in Japanese). 28 December 2018. Retrieved 28 October 2022.
  33. ^ "盗撮のカリスマ”斎藤果林容疑者が逮捕 犯行グループの一員が明かす“卑劣な手口”「若い女性が集まる連休にはグループで“温泉盗撮旅”へ Bunshun Online (in Japanese) May 1 2022. Retrieved June 3 2024.
  34. ^ "「盗撮のカリスマ」率いるグループ16人摘発…男「30年前から1万人は盗撮」" Yomiuri Shimbun (in Japanese) February 2 2023. Retrieved June 3 2024.

Further reading