A vehicle AC generator includes a stator having stator windings; front frame and rear frame, each rotatably supporting a rotor; a cooling fan fitted to the rotor; first polarity arm and second polarity arm configured to rectify currents of one polarity and another polarity, respectively; a rectifier device configured to rectify an alternating current generated in the stator windings; and a protective cover covering the rectifier device. The rectifier device includes a first heat dissipating plate having rectifier elements forming the first polarity arm, a second heat dissipating plate rectifier elements forming the second polarity arm, and a connection plate formed in waveform-like shape and disposed between the first and second heat dissipating plates, and a passage of a cooling air blown by the cooling fan formed between the first and second heat dissipating plates and between the second heat dissipating plate and the connection plate.