A bidirectional non-contact power supply device with its electric power transmission efficiency being high is obtained by a simple configuration. In the bidirectional non-contact power supply device, a coil is included for performing electric power transmission to and reception from another coil through a magnetic field coupling therebetween, and the coil and a capacitor being connected in series are connected on an input-output end of an inverter circuit, wherein a bidirectional buck-boost converter is connected between the inverter circuit and a DC power source (7).