Kenji Sahara
Shigeru Kawamura (as Kenji Sawara)
Yumi Shirakawa
Kiyo
Akihiko Hirata
Dr. Kyuichiro Kashiwagi
Akio Kobori
Police Chief Nishimura
Yasuko Nakada
Female Honeymooner (as Yasuko Nakata)
Minosuke Yamada
Mining Director Osaki
Yoshifumi Tajima
Izeki
Seiji Onaka
Nakagawa, Male Honeymooner (as Kiyoharu Ohnaka)
Keye Luke
Shigeru Kawamura / Sunagawa / Police Officer Toji (voice) (uncredited)
Aya Oyama
Kiyo / Woman Outside Hospital / Female Honeymooner (voice) (uncredited)
George Takei
Dr. Kyuichiro Kashiwagi / Izeki / Male Honeymooner (voice) (uncredited)
Paul Frees
Police Chief Nishimura / Suda / Dr. Tanaka / Air Force Officer / Air Force Pilot Kitahara (voice) (uncredited)
Marvin Miller
Air Self-Defense Force Commander / Air Force Pilot / Newsreader (voice) (uncredited)
James Yagi
Osaki / Professor Minami / Hotel Manager / Farmer (voice) (uncredited)
Jane Chang
Otami (voice) (uncredited)
Art Gilmore
Narrator (voice) (uncredited)
Fay Wray
Screaming Woman in Crowd (voice) (archival) (uncredited)
Murray Spivack
Screaming Police Officers (voice) (archival) (uncredited)
Haruo Nakajima
Rodan / Meganulon (uncredited)
Katsumi Tezuka
Hotel Manager / Rodan / Meganulon (uncredited)
Shōichi Hirose
Fighter Pilot / Meganulon (uncredited)
Tokio Ôkawa
Meganulon (uncredited)