When an AC voltage is outputted to an inductive load, pulsation of an effective power caused by an odd number-th order harmonic component of a current flowing in this load is reduced. A modulation factor k of an inverter 4 includes a DC component k0 and an AC component. The AC component includes a frequency which is a 6n multiple of the fundamental frequency of AC voltages outputted from the inverter. Even when there are not only the 5th order harmonic component of load currents but also the 7th order harmonic component, it is possible to adequately set the ratio of the magnitude of the AC component and the ratio of the DC component and reduce pulsation of consumption power caused by these harmonic components. Reducing the pulsation contributes to suppression of power harmonics.