To surely prevent unintended separation of a C-clip fitted to each axle end part by interposing a button lock assembly as an axle holding and separating mechanism between a pair of right and left axle end parts in a housing of a differential gear, and constantly holding an axial direction clearance between axles.

A housing assembly 12 for demarcating an inner chamber 14 is composed of a main drum 16 and an end part cover 18 fixed to a radial direction flange 20 of the drum 16 by a bolt, and a ring gear for receiving rotating power force or a bevel gear is fixed to the flange 20. End partitions of a pair of output shafts (axles 28a, 28b) are received to the housing assembly 12, a button lock assembly 42 is interposed between button shaped end part pads 32a, 32b arranged on an end part of each axle 28a, 28b, and planetary gear set including side gears 44a, 46b for transmitting a driving torque from the housing assembly 12 to the axles 28a, 28b while allowing speed differential motion between both axles, is built in the housing assembly 12.