NON-CONTACT ELECTRIC POWER FEEDING SYSTEM AND METAL FOREIGN-OBJECT DETECTION APPARATUS FOR NON-CONTACT ELECTRIC POWER FEEDING SYSTEM

A metal foreign object detection device (7) for a contactless power supplying system comprises an antenna coil (AT2), an oscillation circuit (7a) that applies high-frequency current to the antenna coil (AT2), and a detection circuit (7b) that detects a change in voltage or current observed at one of the oscillation circuit and the antenna coil. The oscillation circuit (7a) includes a component having a design value that generates oscillation in a range of oscillation conditions from immediately after the oscillation circuit starts to generate oscillation to just before a stable and continuous oscillation condition. The metal foreign object detection device (7) detects, with the detection circuit (7b), a suspension of the oscillation or an attenuation in amplitude of the oscillation based on a change in an electrical characteristic of the antenna coil (AT2) caused by a metal foreign object arranged on the power supplying device (1).