The first square wave control mode using the square wave pulse pattern is used when the voltage acting on the inverter is equal to or higher than the threshold voltage. On the other hand, when the voltage acting on the inverter is lower than the threshold voltage, a square wave pulse pattern is used when the rotation speed of the motor is equal to or higher than the first predetermined rotation speed that is higher than the first resonance region, and the second square wave control mode using the first switching pattern for suppressing the LC resonance in the first resonance region is used when the rotation speed of the motor is lower than the first predetermined rotation speed.