Center differential unit and planetary gear

A planetary gear type center differential unit contains a carrier (116), a first sun gear (111) and a second sun gear (112) provided interiorly of the carrier, a first (113) and second (114) pinions respectively meshing with the first and the second sun gears, a pinion member having a shaft-receiving hole and carrying the first pinion and the second pinion therearound, and a pinion shaft (119) made of carbon/carbon composite. The pinion shaft is supported by the carrier at one end and is inserted into the shaft-receiving hole of the pinion member, so that the pinion shaft directly supports the pinion member so as to rotate.