Hiroshi Koizumi was born on August 12, 1926, in Kamakura City, Japan. He graduated from Keio University in 1948. He joined NHK television as an announcer and was selected to be part of the third-annual Tôhô New Face acting class in 1951. The following year, Koizumi made his acting debut in Tôhô Studios' _Minato e kita otoko . In the 1990s, Koizumi worked on a few films as producer and also served as host of Japan's long-running game show "Quiz Grand Prix."
Appeared in the first three films to feature the monster Mothra, essentially playing the same role in the latter two films.
He began his show-business career as a television announcer for NHK.
