An inverter includes a warm-up control section and a switching control section. In a state in which an electric motor is not operating, the warm-up control section controls switching elements of an inverter circuit to perform warm-up control, in which direct currents are supplied to the coils of the respective phases of the electric motor, when the temperature of the capacitor is lower than a prescribed temperature. When a warm-up control is switched to a normal operation control, the switching control section sets initial phases of alternating currents such that the relationship between the values of the alternating currents supplied to the coils of the electric motor in the normal operation control matches with the relationship between the values of the direct currents that have been supplied to the corresponding coils of the electric motor in the warm-up control.