An abnormality diagnosis method for diagnosing an abnormality of a ground power supply device that transmits electrical power to a vehicle in a wireless manner includes: performing a power supply operation under a plurality of different power supply conditions when the vehicle is located on a power transmission coil of the ground power supply device; and diagnosing an abnormality of the ground power supply device based on a value of a parameter related to power supply detected while the power supply operation is performed under the plurality of different power supply conditions.
