CONTACTLESS CHARGING SYSTEM AND CONTACTLESS CHARGING METHOD

A contactless charging method according to the present invention is applied to a contactless charging system 1 which comprises a transmitting unit 10 having a primary coil 11 and a receiving unit 20 having a secondary coil 21 and which charges a battery 30 electrically connected to the secondary coil 21 by the electromagnetic induction generated between the primary coil 11 and the secondary coil 21 and which supplements the charging efficiency of the battery 30 by varying a charging frequency used in the electromagnetic induction in proportion to the charging efficiency of the battery 30 that varies according to the position of the secondary coil 21 relative to the primary coil 11. The contactless charging method comprises: a step of detecting a charging frequency when a charging operation is performed by enabling the primary coil 11 to get close to the secondary coil 21; and a step of outputting the charging efficiency of the battery 30 acquired from the detected charging frequency such that a user may know the charging efficiency.