In a wireless power supply apparatus, a first unit electrically connected to a power supply and a second unit electrically connected to an electric load. Power transmission is performed wirelessly between the first and second units using a magnetic resonance phenomenon. Each of the units has a resonant amplifier circuit provided with switching means driven by a drive signal, a resonant coil to which a high-frequency signal generated by the resonant amplifier circuit is supplied such that the resonant coil functions as a resonant inductor on the resonant amplifier circuit, and electric storage means electrically connected to the resonant amplifier circuit so as to be capable of charging and discharging power. The second unit includes current detecting means for detecting a current flowing through the storage means, and phase control means for controlling a phase of the drive signal for the switching means based on the detected current.