A transmission for an auxiliary device arranged for transmitting a driving force of an engine to an auxiliary device has a planetary-gear-type speed increasing mechanism having a first gear driven by the engine through an input shaft, a second gear connected to the auxiliary device and a third gear for locking. It is further provided with a friction clutch for connecting the third gear to a stationary member, a hydraulic actuator for pressing the friction clutch and an oil pump for feeding an oil pressure to the hydraulic actuator. A damper is disposed between the stationary member and the friction clutch.
