Abstract: A vehicle alternator for generating electric power has a stator, a rotor, a rectifier, a regulator case, and a cooling fin part. A stator winding is wound on the stator. The rotor is placed on opposite faces to the stator. The rectifier rectifies an alternating current output voltage excited in the stator winding. The regulator case accommodates a regulator substrate for adjusting the output voltage and a heat sink. On one surface of the heat sink the regulator substrate is mounted. The cooling fin part has plural cooling fins bonded to the other surface of the heat sink. The cooling fin part and the heat sink are made of a same material of a superior thermal expansion coefficient, such as copper or copper alloy.