PURPOSE: To obtain the self-exciting AC generator of a capacitor exciting type for enabling voltage at both ends of a capacitor, field winding current, and load voltage, to be prevented from being excessively increased.

CONSTITUTION: Into a space between a capacitor exciting winding Wc and a capacitor C arranged on the stator S of the self-exciting AC generator of a capacitor exciting type, a breaker Br is inserted. When the electrifying current Ic of the capacitor exciting winding Wc comes to a set value or more, then the breaker Br is opened, and voltage at both ends of the capacitor C is prevented from being excessively increased.