Takashima began participating in a jazz band while a student at Kwansei Gakuin University. He left the university before graduating when he joined the Shintoho studio, debuting as an actor in 1952. He starred in the 1962 film King Kong vs. Godzilla alongside Yū Fujiki, and subsequently acted with Fujiki in several comedy films about salarymen, which were popular in Japan at that time. Takashima also appeared in Son of Godzilla and Godzilla vs. Mechagodzilla II.

He gained popularity as a romantic lead who could also sing, which led to roles in stage musicals, including the role of Professor Henry Higgins in a 1963 production of My Fair Lady. He also appeared on several television programs, including the quiz show Quiz! Do-re-mi-fa-don! and the cooking show Gochisosama.

In 1963, Takashima married Hanayo Sumi, a former member of Takarazuka Revue. His first-born son was murdered in 1964 at the age of five months by the family maid. He had two other sons, Masahiro Takashima and Masanobu Takashima, both of whom are actors. In 1998, Takashima developed depression, from which he subsequently recovered.

Takashima died of natural causes in his home in Tokyo on 26 June 2019 at age 88.