In a wireless power supply system including a power feeding system (2) equipped with a transmission antenna (5) for wirelessly transmitting an electric power from a power source, and a receiver antenna (12) formed by winding a receiver coil (12b) around an outer periphery of a substantially bar-like core member (12a) for receiving the transmitted electric power, the length of the core member of the receiver antenna is more than 10 times longer than the diameter of the core member.