The Seinenza Theater Company (劇団青年座, Gekidan Seinenza) is a Japanese theatre company located in Shibuya, Tokyo. It was founded on December 17, 1954 and stages Shingeki plays. Many of its actors have gone on to become voice actors for anime productions.

Notable members

Former members

• Jūkei Fujioka (deceased)
• Kōe Hatsui (deceased)
• Tomoyuki Dan (deceased)
• Manabu Ino
• Daisuke Koshikawa
• Gin Moritsuka (deceased)
• Mosahiko Naruse
• Toshiyuki Nishida
• Naoto Ogata
• Sumi Shimamoto
• Kōsuke Suzuki
• Naoto Takenaka
• Hideyuki Tanaka
• Hisano Yamaoka (deceased)
• Yō Yoshimura (deceased)