PURPOSE: To increase the cooling efficiency of a clutch disk by providing fins projected in the direction of a pressure plate and an opening opened on the upstream side of the rotation, on a disk plate.

CONSTITUTION: A clutch disk 10 is provided with a disk plate 1 and two frictional facings 16, and air grooves are formed in these frictional facings 16 to cool the frictional surfaces by the flown air. Multiple hemispherical fins 3 are formed on the disk plate 1 and an opening 2 is provided upstream the rotation. Also, an opening 4 is provided on the surface of the disk plate to connect it to the air inlet portion (opening) 2. Thus, air is led into a flywheel side clearance to prevent the temperature at the frictional facing from being raised excessively, whereby the clutch service life is prolonged.