A normal map determines a carrier frequency used for switching control of an inverter controlling driving of a motor generator, in accordance with the state of operation of the motor generator in a normal operation. In a stall state in which the driver is pressing both the accelerator pedal and the brake pedal, the switching frequency is determined using an element protection map, in place of the normal map. When the element protection map is used, in the state of operation corresponding to the stall state, the carrier frequency is set to a protection frequency lower than a normal frequency. Therefore, in an electric vehicle having an electric motor (motor generator) as a driving source for the vehicle, it becomes possible to avoid temperature increase of a power semiconductor device forming an electric power converter for controlling driving of the electric motor.