Akira Takarada as Lt. Commander Jiro Nomura

Mie Hama as Madame Piranha

Rhodes Reason as Commander Carl Nelson

Linda Miller as Lieutenant Susan Watson

Hideyo Amamoto as Dr. Who

Yoshibumi Tajima as Henchman

Sachio Sakai as Henchman

Ryuji Kita as SDF General

Ikio Sawamura as Native

Nadao Kirino as Henchman

Shōichi Hirose as Henchman

Kazuo Suzuki as Henchman

Tōru Ibuki as Henchman

Naoya Kusakawa as

Susumu Kurobe as Henchman

Haruo Nakajima as King Kong

Hiroshi Sekita as Mechani-Kong/Gorosaurus

Kei Taguchi as (voice)

Akiko Santo as (voice)

Osman Yusuf as Submariner (uncredited)

Tadashi Okabe as Soldier (uncredited)

Seishirō Kuno as Soldier (uncredited)

Yasuhisa Tsutsumi as General (uncredited)

Andrew Hughes as Reporter (uncredited)