To prevent incomplete combustion due to negligence of returning and breakage of an exhaust catalyst by automatically returning a starter operating knob to its original point at the time when engine temperature reaches certain temperature even in the case when a driver forgets returning of the starter operating knob.

A plural number of cutouts 14 are formed on a starter shaft 10 interlocked with a starter plunger 20 to open and close a fuel passage 26 for starting, and a return spring 28 to return the starter plunger 20 is furnished. A working rod 32 of a solenoid 30 is arranged in the vertical direction against a shaft of the starter shaft 10, a ball 36 is furnished on its head end through a presser spring 34, and this ball 36 is made contact with the starter shaft 10. At the time when an engine is high temperature, force of the return spring 28 to return the starter plunger 20 is superior to force to hold the starter shaft 10 at a specified position by the ball 36, and the starter plunger 20 returns.