A differential device for a 4-wheel-drive vehicle wherein a portion of a drive power source drive force transmitted to left and right main drive wheels is transmitted to left and right auxiliary drive wheels through a propeller shaft which is disconnectable from a power transmitting path between the main drive wheels and drive power source, the differential device distributes the drive force from the propeller shaft to the auxiliary drive wheels, and selectively connects and disconnects the propeller and an output shaft to and from each other, the output shaft. The differential device includes a side oil seal between the output shaft and a casing, a side bearing adjacent to the seal in an output shaft axial direction such that the output shaft is rotatably supported by the casing via the bearing, and an oil slinger axially adjacent to the bearing so the slinger is rotated with the output shaft.