A wireless power transmission apparatus 1 includes a power-supplying module 2, a power-receiving module 3, a phase detector 4, and a control device 5, and is set so that its transmission characteristic with respect to the power-source frequency has a double-hump characteristic. The control device 5 determines whether to supply power to the power-supplying module 2, based on variation in the phase of the input impedance Zin in the power-supplying state and that in the standby state, which is detected by a phase detector 4.