A differential device includes: an input member; a case member arranged coaxially with the input member; a one-way clutch arranged between the input member and the case member and transmitting torque therebetween only when the input member attempts to rotate in a normal rotation direction; a pinion gear supported by the case member to rotate about the axis perpendicular to the center axis of the case member; and a pair of side gears supported coaxially with the input member to rotate relative to the input member and the case member and meshing with the pinion gear.