(As of June 2022, 8)

Honorary chairman

  • October 1994 - March 11
    Masamitsu Oshima (passed away in May 2010)

Chairman/Vice Chairman

  • October 1983 - March 4
    Chairman: Masamitsu Oshima
    Vice Chairman: Mitsuharu Okajima
  • October 1994 - March 11
    Chairman: Shigeyoshi Kaihara (passed away in January 2011)
    Vice Chairman: Michitoshi Inoue
  • October 1997 - March 11
    Chairman: Yoichi Satomura
    Vice Chairman: Michitoshi Inoue
    Vice Chairman: Takashi Takahashi
  • October 2000 - March 11
    Chairman: Michitoshi Inoue
    Vice Chairman: Hiroshi Tanaka
    Vice Chairman: Kazunobu Yamauchi
  • November 2003 to June 11 (2004st period)
    Chairman: Hiroshi Tanaka
    Vice Chairman: Michio Kimura
    Vice Chairman: Kazunobu Yamauchi
  • June 2004 to June 6 (2007nd to 6th period)
    Chairman: Hiroshi Tanaka
    Vice Chairman: Michio Kimura
    Vice Chairman: Kazunobu Yamauchi
  • June 2007 to June 6 (2010nd to 6th period)
    Chairman: Ryuichi Yamamoto
    Vice Chairman: Michio Kimura
    Vice Chairman: Kotaro Sakurai
  • June 2010 to June 6 (2013nd to 6th period)
    Chairman: Michio Kimura
    Vice Chairman: Kazuhiko Oe
    Vice-chairman: Mihoko Okada
  • June 2013 to June 6 (2016nd to 6th period)
    Representative Director: Mihoko Okada
    Vice Representative Director: Naoki Nakajima
    Vice representative director: Masaki Miyamoto
  • June 2016 to June 6 (2019nd to 6th period)
    Representative Director: Kazuhiko Oe
    Vice Representative Director: Tomohiro Sawa
    Vice representative director: Yasushi Matsumura
  • June 2019 to June 6 (2022nd to 6th period)
    Representative Director: Naoki Nakajima
    Vice Representative Director: Katsuyuki Kondo
    Vice Representative Director: Tomohiro Sawa