To provide a differential mechanism capable of stably being supported with a simple structure in a transmission case, satisfactorily transmitting a rotation of a rotation shaft, and allowing efficient and easy maintenance work of the rotation shaft or an axle.

In this differential mechanism 3, a pair of facing pinion gears 32 are journalled via a pin shaft 31 in a plate-like differential gear case 30 supported in a transmission case 5, and right and left side gears 33 are respectively meshed to the pair of pinion gears 32 from both sides to differentially drive a rotation shaft 6 connected to each side gear 33. Receiving portions 33a are formed on the right and left side gears 33, metals 53 are inserted into the respective receiving portions 33a, and the transmission case 5 intermediately packaging the differential mechanism 3 rotatably supports the differential mechanism 3 via the metals 53.