Wireless power supply apparatus for linear motion type robot

A wireless power supply apparatus using magnetic resonance is provided for a linear motion type robot. In the apparatus, a high-frequency signal for foreign matter detection is generated. This signal is different in wavelength and frequency from a high-frequency signal for transmitting power between a power transmission coil and a power reception coil. The wavelength is wavelength [lambda] and the frequency is frequency f. The power transmission coil serves as an apparent antenna of which the long side is set to [lambda]/2. At least either of a wavelength [lambda]x or a resonance frequency fx of a resonance wave attributed to the resonance in the antenna is detected when the high-frequency signal is supplied to the antenna. Whether or not foreign matter is present on the power transmission coil is detected based on the wavelength [lambda]x or the resonance frequency fx.