An electric rotating machine for a vehicle is equipped with a load dump protector. The load dump protector works to selectively perform a first and a second load dump protection operation to suppress a voltage surge arising from the load dump. When a rate at which an output voltage from the electric rotating machine is determined to be smaller than a given value, the load dump protector waits for stating the first load dump protection operation until the time when a voltage surge arising from changing of switching devices of a rectifier module of the electric rotating machine is expected to be suppressed and then performs the first load dump protection operation. When the rate is greater than the given value, the load dump protector immediately initiates the second load dump protection operation. This ensures the stability in eliminating the risk of a voltage surge arising from the load dump.