To avoid driving an AC generator at an accelerated state at all times by combining an epicyclic gear mechanism with a clutch already provided for a vehicle, to prevent over-heating, and to enhance the durability of a rotary portion at low cost.

This generator device for a vehicle is provided with a clutch inner 21 to be integrally rotated with a crank shaft, a starting clutch 20 including a clutch outer 22 to be connected with the clutch inner 21 to transfer torque to an output shaft 15 when the revolution number of engine exceeds the number of prescribed revolutions higher than the number of idling revolutions, a sun gear 31 to be integrally rotated with the rotating shaft 41 of the AC generator, an annular gear 34 to be integrally rotated with the output shaft 15, and with a epicyclic gear mechanism rotatably supporting an epicyclic gear 32, and having a carrier 33 to be integrally rotated with the clutch inner 21.