Patent ID: 8382632

Claim:
A differential gear comprising: a ring gear configured to be rotated by a driving force inputted thereto from a driving source; a differential case configured to be rotated together with the ring gear; a pinion shaft assembled on the differential case, the pinion shaft being configured to be rotated together with the differential case; pinion gears rotatably mounted on the pinion shaft; and side gears configured to be meshed with the pinion gears; the differential case including a first boss part into which a first drive shaft is inserted, and a second boss part into which a second drive shaft opposed to the first drive shaft is inserted; wherein: the differential case is composed of: a first case body being made of a single material and extending from pinion-shaft assembling parts on which the pinion shaft is assembled, to the ring gear, the first case body having an aperture that receives the pinion shaft; a second case body having the first boss part; and a third case body having the second boss part; the first case body is integrally formed by forging; the second case body is integrally formed by forging; the third case body is integrally formed by forging; the first case body and the second case body are joined to each other by welding; and the first case body and the third case body are joined to each other by welding.