A wireless power feeder which performs power feed by a non-contact method to a wireless power receiver having a power receive coil, this wireless power feeder having a power feed coil; and a control circuit having a phase delay device which generates a delayed AC voltage where the phase of the output AC voltage is delayed; a magnetic sensor biased by the delayed AC voltage and detects a magnetic field generated by power receive coil; phase detection circuits which generate phase difference instruction voltages corresponding to a phase difference between an output voltage from the magnetic sensor and a comparison voltage, on the basis of the output voltage and the comparison voltage; and AC current generation circuits which generate the output AC voltage having a frequency based on the phase difference instruction voltage, and generate the AC current having a frequency corresponding to the frequency of the output AC voltage.