A rear wheel driving device includes first and second electric motors, a wet multi-plate type hydraulic brake provided on motive power transmission paths between the first and second electric motors and rear wheels Wr and causing the drive source side and the wheel side to become disconnected state or connected state by being released or fastened, and a control device that controls switching between the disconnected state and the connected state of the hydraulic brake and controls a vehicle speed. The rear wheel driving device further includes a viscosity acquisition unit that acquires a viscosity correlation amount of oil provided to cool plates of the wet multi-plate type hydraulic brake, and the control device fastens the hydraulic brake or maintains fastening thereof and controls the vehicle speed to lower than a first speed in a case where the viscosity correlation amount is a first prescribed value or higher.