To make a high efficiency electric power feeding possible without a wireless communication.There is provided an electric power feeding apparatus 100 for feeding a secondary coil 210 of a moving body 200 with an electric power, which comprises a primary coil 140 that is magnetically coupled with the primary coil with the work of resonance of a magnetic field and constructed to supply a high frequency electric power to the secondary coil 210, a high frequency electric power driver 120 that converts, by causing a magnetic field to resonate, the electric power from an alternating-current power supply 110 to a high frequency electric power that can transfer to the moving body 200 and feeds the primary coil 140 with the converted electric power, a calculation device 130 that estimates, from supplying current and voltage of the high frequency electric power driver 120, equivalent circuit parameters of an electric power transfer from the primary coil 140 to the secondary coil 210 upon resonance of the magnetic field, and a control device 150 that estimates, from the equivalent circuit parameters estimated by the calculation device 130, the receiving electric power of the secondary coil 210 and controls the high frequency electric power driver 120 in such a manner as to cause the estimated receiving electric power to show the maximum value.