Wireless power transmitter, wireless power receiver, and power transmission method of wireless power transmitting system

A wireless power transmitter (200) for transmitting power to a wireless power receiver (300) in a wireless scheme includes a transmitting coil (L2) configured to transmit power, which is supplied by a power source (100), to a receiving coil (L3) of the wireless power receiver using resonance; and a detecting unit (220) configured to detect a coupling state between the transmitting coil (L2) and the receiving coil (L3) using an input impedance (Z1) of the wireless power transmitter (200).