The present disclosure includes a feed unit and a feed system. The feed unit includes a power transmission coil and a coupling coefficient calculation section. The power transmission coil is configured to transmit power to a power reception coil of a receiving unit using a magnetic field. The coupling coefficient calculation section is configured to measure frequency characteristics of input impedance of a rectification circuit of the receiving unit, the rectification circuit being in a non-operating state. The coupling coefficient calculation section is also configured to calculate a coupling coefficient between the power transmission coil and the power reception coil using the frequency characteristics of the input impedance of the rectification circuit that have been measured.