An alternator for a vehicle has a regulator disposed in a casing so as to be exposed from a window of the casing, an input harness and an output harness disposed outside the casing, and an insulating bush disposed between an output terminal and the casing. The regulator controls generation of electric power in response to a control signal sent through the input harness and a connector disposed on the casing. The generated power is output from the alternator through the output terminal and the output harness. The alternator further has a shield cover connected with the insulating bush so as to be unified with the insulating bush. An exhaust pipe heated at a high temperature is disposed over the casing. The shield cover extends between the casing and the exhaust pipe so as to shield the regulator and the harnesses from the exhaust pipe.