A vehicle alternator includes a case having a pair of brackets placed back-to-back, in which ribs are disposed, which define ventilation windows (29; 74) in a bracket body. The ribs serve as heat passage members (54, 60; 73), which have higher thermal conductivity than the bracket body and are partially embedded in the bracket body. Therefore, heat resistance in the heat transfer passage between the stator and the ventilation windows is reduced, and heat generated by the stator is expelled efficiently from the ventilation windows to the outside air, and the temperature of the stator can be reduced.