As illustrated in FIGS. 22A and 22B, when an inverter of the wireless power transmitter 100 suspends the operation while driving the LC resonant circuit, the resonant energy of the resonant circuit of the wireless power transmitter 100 gradually decreases. Taking a current of L for a value representing the energy of the LC resonant circuit of the wireless power transmitter 100 as an example, when the current of L is changed from a first current (I1) to a second current (I2) based on a value the following Equation 2 is established.