A SS-method bidirectional contactless power supply device is arranged such that at the time of G2V, a second power converter converts commercial alternating current to direct current, a first power converter converts the direct current to high-frequency alternating current, and a third power converter converts the high-frequency alternating current to the direct current to charge an electric storage device. On driving the first power converter with a constant voltage, the electric storage device is charged with a constant current. At the time of V2G, the third power converter converts the direct current to the high-frequency alternating current, the first power converter converts the high-frequency alternating current to the direct current, and the second power converter converts the direct current to the commercial alternating current. On driving the third power converter with the constant current, an output of the first power converter becomes the constant voltage.