In an AC generator, a protective cover includes a locking claw provided so as to extend outward in an axial direction from an open-side end surface of a peripheral wall portion. The locking claw includes an axial portion and a claw portion provided so as to project radially from an end portion of the axial portion. The locking claw is configured to be locked to a casing. The protective cover also includes a locking-claw restricting portion formed on an outer peripheral edge portion of a bottom portion.