 Raymond BurrSteve Martin | Steve Martin |
 Akira TakaradaOgata | Ogata |
 Akihiko HirataDr. Serizawa | Dr. Serizawa |
 Takashi ShimuraDr. Yamane | Dr. Yamane |
 Momoko KôchiEmiko Yamane | Emiko Yamane |
 Emilio CigoliSteve Martin (voice) | Steve Martin (voice) |
 Rita SavagnoneEmiko Yamane (voice) | Emiko Yamane (voice) |
 Giuseppe RinaldiOgata (voice) | Ogata (voice) |
| VVittorio CramerGeorge Lawrence (voice) (as Vittorio Kramer) | George Lawrence (voice) (as Vittorio Kramer) |
| PPino LocchiSecurity Officer Tomo Iwanaga (voice) | Security Officer Tomo Iwanaga (voice) |
 Gianfranco BelliniDr. Serizawa (voice) (uncredited) | Dr. Serizawa (voice) (uncredited) |
| BBruno PersaDr. Yamane (voice) (uncredited) | Dr. Yamane (voice) (uncredited) |
 Sachio SakaiHagiwara (uncredited) | Hagiwara (uncredited) |
 Fuyuki MurakamiDr. Tabata (uncredited) | Dr. Tabata (uncredited) |
 Ren YamamotoSeiji (uncredited) | Seiji (uncredited) |
| TToyoaki SuzukiShinkichi (uncredited) | Shinkichi (uncredited) |
 Tadashi OkabeDr. Tabata's Assistant (uncredited) | Dr. Tabata's Assistant (uncredited) |
 Toranosuke OgawaPresident of Company (uncredited) | President of Company (uncredited) |
 Frank IwanagaSecurity Officer Tomo Iwanaga (uncredited) | Security Officer Tomo Iwanaga (uncredited) |
 Mikel ConradGeorge Lawrence (uncredited) | George Lawrence (uncredited) |
 Kokuten KōdōThe Old Fisherman (uncredited) | The Old Fisherman (uncredited) |
 Kenji SaharaMan on Boat (uncredited) | Man on Boat (uncredited) |
 Haruo NakajimaGodzilla (uncredited) | Godzilla (uncredited) |
 Katsumi TezukaGodzilla (uncredited) | Godzilla (uncredited) |
