A vehicle AC generator for charging a battery includes a rotor having a permanent magnet, a stator having an armature winding, a rectifier and a short-circuit unit. The short-circuit unit intermittently short-circuits the armature winding. The armature winding is set to generates a no-load voltage that is lower than a terminal voltage of the battery when the armature winding is not connected to loads. The short-circuit unit intermittently short-circuits the armature winding to generates a fly back voltage that is higher than the terminal voltage of the battery when the armature winding is connected to the loads. Therefore, the output voltage of the permanent magnet type generator can be regulated without significant energy loss.