A power generator for which assembly work can be performed under a state in which a separable body is separated from a first frame portion and a first partition plate portion when a stator is assembled inside a frame. Therefore, an end bell to be integrated with a second partition plate portion has a small diameter, and can be arranged close to a rotor. As a result, the end bell made of an insulating resin can be arranged only in a portion in which a flux-loss reduction effect is significant.