A starter which applies a mechanical rotating force to a rotor of an electromagnetic converter, such as a power generator, for startup of the rotor. The starter includes a startup spring (60) having an engaging portion (63) engageable with a 6th pinion (11a) of a wheel train coupled to the power generator. In interlock with the operation of pulling out a crown, a reset lever (70) is operated to bias the startup spring for engagement with the 6th pinion. Thereafter, the startup spring is released from the biased state in interlock with the operation of pushing in the crown. The startup spring is returned to the original position due to its own spring force, whereupon a mechanical rotating force is applied to the pinion. Since the rotating force can be set by a resilient force of only the startup spring, a stable rotating force is applied to the rotor (12).