To provide a cooling device can properly cool an electric motor by considering a traveling mode of a vehicle.

This cooling device includes an electric pump 24 for supplying a cooling medium to a motor generator 22 mounted on the vehicle, and an ECU 30 for controlling an operation of the electric pump 24 and detecting an operation of a changeover switch to switch a first traveling mode and a second traveling mode in which a characteristic of driving force in relation to an accelerator operation of a driver is made a characteristic of higher driving force than that of the first traveling mode. When the first traveling mode is set by the detected operation of the changeover switch, the ECU 30 operates the electric pump 24 when a temperature of the motor generator 22 is a temperature threshold value set in advance or more. When the second traveling mode is set by the detected operation of the changeover switch, the ECU 30 operates the electric pump 24, even if the temperature of the motor generator 22 is less than the temperature threshold value.