- Mugen Decal.jpg|thumb|130px|right]]
Mugen Motorsports is a Japanese company formed in 1973 by Hirotoshi Honda, the son of Honda Motor Company founder Soichiro Honda, and Masao Kimura. Mugen, meaning "Without Limit", or "Unlimited", (hence the commonly placed word "Power" after, denoting "Unlimited Power") is an engine tuner and parts manufacturer closely associated with the Honda Motor Company. Despite the family connections, however, Mugen is not, and has never been, owned by Honda. Things were complicated for some time as Mugen was owned and run by Hirotoshi Honda, who has been the major shareholder in Honda since his father's death in 1991.
The company tunes and races Honda vehicles in the Super GT championship, and, additionally, sells aftermarket parts to amateur enthusiasts. It was part of partnerships that won the Formula 3000 championship in 1990 and 1991, and that eventually led to Mugen's involvement in Formula One, from 1992 to 2000, and up to 2005 was the exclusive supplier of Formula Nippon engines.