The Japan Steel Works, Ltd.
Company typePublic (K.K)
TYO: 5631
OSE: 5631
NAG: 5631
FSE: 5631
Nikkei 225 Component
IndustryIndustrial machinery
FoundedNovember 1, 1907; 116 years ago (1907-11-01)
HeadquartersGate City Ohsaki-West Tower, 11-1, Osaki 1-chome, Shinagawa-ku, Tokyo 141-0032, Japan
Key people
Ikuo Sato (CEO and President)
Revenue$ 2.346 billion USD (FY 2012) (¥ 220.65 billion JPY) (FY 2012)
$ 88.04 million USD (FY 2012) (¥ 8.28 billion JPY) (FY 2012)
Number of employees
4,804 (consolidated) (as of March 2013)
WebsiteOfficial website
Footnotes / references

The Japan Steel Works, Ltd. (株式会社日本製鋼所, Kabushiki Kaisha Nihon Seikōsho) is a steel manufacturer founded in Muroran, Hokkaidō, Japan in 1907.[3]


Japan Steel Works was set up with investment from British firms Vickers, Armstrong Whitworth and Mitsui.[3] During World War II, they manufactured what was then the world's largest gun barrel to be fitted on the battleship Yamato. 200 workers in their main plant in Muroran were killed in a 1945 attack by Allied Forces.[4]


Japan Steel Works' industrial processes which are used to purify steel are held to high standards. These include the use of argon gas to eliminate impurities, and the addition of manganese, chromium and nickel to make the steel harder.[4]

Japan Steel Works' services are in great demand owing to its role as one of only five manufacturers worldwide of the largest single-piece components of Reactor pressure vessels for nuclear reactors[4][5] at the company's factory, which is located on the island of Hokkaidō. The other manufacturers as of 2010 are two companies in China, one in Russia (Atomenergomash) and one in France (Framatome).[6] However, Japan Steel Works is the only one that can make cores in a single piece without welds, which reduces risk from radiation leakage.[7] The company has boosted production to 6 units per year from 4 previously of the steel pressure vessel forgings, which contain the nuclear reactor core. It is scheduled to take capacity to 11 by 2013.[7] Due to the production bottleneck, utilities across the world are submitting orders years in advance of any actual need, along with deposits worth hundreds of millions of dollars. Other manufacturers are examining various options, including finding ways to make a similar item using alternate methods, or making the component themselves with welds.[4] However, welds are weak points which can result in reactor leakage.

Other items manufactured by Japan Steel Works include machines for processed plastics.[8] They also continue to make a limited number of traditional Japanese swords.[4] They are also involved in the development of the Type 10 battle tank, Type 99 155 mm self-propelled howitzer and Naval artillery.

Financial information

In fiscal year 2001, Japan Steel Works posted a net loss of ¥1.81 billion on sales of ¥119.70 billion. Their performance improved in 2002, with net profit of ¥100 million on sales of ¥129 billion; however, this was far short of their earlier estimate of ¥600 million net profit on sales of ¥134 billion.[8]

Japan Steel Works Ltd. increased net profit to ¥12.6 billion for the nine months to December 31, 2007. Revenue was up to ¥159.2 billion. Operating profit increased to ¥21.9 billion and ordinary profit rose to ¥21.2 billion. Full-year revenue forecast is unchanged at ¥ 218 billion to March 31, 2008. The company maintained a full-year net profit forecast of ¥15 billion.[9]


See also


  1. ^ "Japan Steel Works Annual Report 2013" (PDF). Archived from the original (PDF) on March 14, 2014. Retrieved March 14, 2014.
  2. ^ "Corporate Profile". Retrieved March 14, 2014.
  3. ^ a b "会社情報 (Company information)", Official website, Japan Steel Works, Ltd., retrieved March 14, 2008
  4. ^ a b c d e Takemoto, Yoshifumi; Katz, Alan (March 13, 2008), "Bloomberg exclusive: Samurai-Sword Maker's Reactor Monopoly May Cool Nuclear Revival",, retrieved March 14, 2008
  5. ^ Kid, Steve (March 3, 2009), "New nuclear build – sufficient supply capability?", Nuclear Engineering International, archived from the original on June 13, 2011, retrieved January 17, 2011
  6. ^ Heavy Manufacturing of Power Plants, World Nuclear Association, December 2010, archived from the original on November 8, 2010, retrieved January 17, 2011
  7. ^ a b Suga, Masumi; Song, Yasumasa (June 1, 2010), "Japan Steel to Sell Parts for 26 Nuclear Reactors", BusinessWeek, retrieved January 17, 2011[dead link]
  8. ^ a b "Japan Steel Works revises downward earnings for year to March.", Japan Weekly Monitor, March 20, 2002, retrieved March 14, 2008
  9. ^ "Japan Steel Works Ltd. (5631): Stock Quote & Company Profile", BusinessWeek, archived from the original on January 27, 2008, retrieved January 17, 2011