WIRELESS POWER SUPPLY DEVICE

A wireless power supply device (101) includes a resonant circuit (111) comprising a power supply coil (111a) and a resonant capacitor (111b); and a controller that changes a waveform of power in the resonant circuit (111) and causes a phase difference between a phase of a drive signal that drives the resonant circuit (111) and a phase of current flowing through the power supply coil (111a) to be substantially 0.