A contactless power transmission apparatus includes a secondary device that includes a resonant circuit including a second transmitter coil that transmits and receives electric power to and from a first transmitter coil included in a primary device and a resonant capacitor connected in parallel to the second transmitter coil, a second converter circuit connected to the resonant circuit to convert alternating current power flowing through the resonant circuit to direct current power and convert direct current power to alternating current power flowing through the resonant circuit, a coil connected in series to the second transmitter coil between the resonant circuit and the second converter circuit, and a capacitor connected in series to the second transmitter coil between the second transmitter coil and the second converter circuit.