It has been confirmed by Sega that Mike Hayes, the CEO of the companies North American and European operations, has left his position at the company.
Since 2004 Hayes has overseen Sega's transformation from platform holder to software developer and publisher.
Naoya Tsurumi, president and representative director, said: "Mike has achieved a huge amount during his time at SEGA and we thank him for the amazing things he has accomplished."
"Mike is a great character and very passionate about the industry, he helped steer the extraordinary growth of SEGA and has built an exceptional team of professionals that will stand us in good stead for the future."