After turning on a switching element by receiving a discharge command from a motor ECU via a control circuit, a drive circuit of a discharge device causes, upon receipt of an overheat protection command from an overheat protection circuit, the switching element to turn off and keeps the resulting state thereof. And, the motor ECU sends the discharge command, after establishment of a diagnostic condition, to the control circuit of the discharge device and determines that the discharge device is abnormal if an electric current will not flow through a discharge resistor and the switching element.