Raymond Burr as Steve Martin

Takashi Shimura as Dr. Yamane

Momoko Kôchi as Emiko Yamane

Akira Takarada as Ogata

Akihiko Hirata as Dr. Serizawa

Sachio Sakai as Hagiwara

Fuyuki Murakami as Dr. Tabata

Ren Yamamoto as Seiji

Toyoaki Suzuki as Shinkichi

Tadashi Okabe as Dr. Tabata's Assistant

Toranosuke Ogawa as President of Company

Frank Iwanaga as Security Officer Tomo Iwanaga

Sammee Tong as Dr. Yamane / Dr. Tabata (voice) (uncredited)

James Hong as Ogata / Dr. Serizawa / Hagiwara (voice) (uncredited)

Mikel Conrad as George Lawrence (uncredited)

Paul Frees as Unidentified Character (voice) (uncredited)

Hiroshi Hayashi as Chairman of Diet Committee (uncredited)

Ren Imaizumi as Radio Operator (uncredited)

Kokuten Kōdō as The Old Fisherman (uncredited)

Takeo Oikawa as Chief of Emergency Headquarters (uncredited)

Tsuruko Mano as The Boy's Mother (uncredited)

Kenji Sahara as Man on Boat (uncredited)

Kin Sugai as Ozawa-san (uncredited)

Lee Miller as Man in Line at Airport (uncredited)

Haruo Nakajima as Godzilla (uncredited)

Katsumi Tezuka as Godzilla (uncredited)

Ryosaku Takasugi as Godzilla (uncredited)