A brushless alternating current generator for vehicles comprises a stator, rotor, field winding, rectifier, housing, cover, and extension member. The rectifier has plural rectifying elements to rectify a voltage from the stator winding and output the rectified voltage and a radiating fin to which the rectifying elements are attached. The housing has a side wall and houses both the stator and the rotor and has an end face to which electric parts including the rectifier are attached. The side wall is along the axial direction. The end face is along the radial direction. Both the side wall and the radiating fin are mutually adjacent to provide a gap in the radial direction. The cover encloses the end face of the housing and has plural air inlets that takes in cooling air. The extension member is secured to the cover and extends into the gap in the axial direction.