Hiroshi Koizumi as Tsukioka

Setsuko Wakayama as Hidemi

Minoru Chiaki as Kobayashi (as Mindru Chiaki)

Takashi Shimura as Dr. Yamane

Masao Shimizu as Dr. Tadokoro

Seijirô Onda as Commander (as Serjiro Onda)

Sonosuke Sawamura as Shibeki

Yoshio Tsuchiya as Tajima

Mayuri Mokushô as Radio Operator

Yukio Kasama as Father (as Yokio Kasama)

Takeo Oikawa as Police Chief

Minosuke Yamada as Chief of Civil Defense (uncredited)

Ren Yamamoto as Ikeda (uncredited)

Shin Ōtomo as Convict Leader (uncredited)

Senkichi Ōmura as Convict (uncredited)

Haruo Nakajima as Gigantis (uncredited)

Katsumi Tezuka as Angurus (uncredited)

Shōichi Hirose as Convict (uncredited)

Keye Luke as Tsukioka / Policeman (voice) (uncredited)

Aya Oyama as Hidemi (voice) (uncredited)

Marvin Miller as Kobayashi / Dr. Yamane / Narrator (voice) (uncredited)

Paul Frees as Commander / Father / Convict (voice) (uncredited)

George Takei as Ikeda / Osaka SDF Dispatcher (voice) (uncredited)

Jane Chang as Radio Operator (voice) (uncredited)

James Yagi as Osaka SDF Captain (voice) (uncredited)