Koichi Sasaki reportedly sold fake insurance policies, issued customers with counterfeit insurance certificates and pocketed the premiums.
Sasaki joined Gibraltar Life Insurance in January 2012 when the company merged with AIG Edison Life Insurance. His actions came to light in August 2016.
The company said it has conducted an internal investigation and contacted the police about filing a criminal complaint against Sasaki.
Founded in Japan in 1935 under the name Kyoei Life Insurance, the company changed its name to Gibraltar Life Insurance in 2001. It sells life insurance products and services in Japan.
Despite its name, there is no apparent link to the British overseas territory of Gibraltar.