An in-vehicle wireless electric power feeding device is used in a vehicle, wirelessly performs electric power feeding to an electric power reception device (e.g., smartphone), and stops the electric power feeding at a temperature not lower than or higher than a predetermined first temperature threshold. The in-vehicle wireless electric power feeding device SD includes an electric power transmission unit that wirelessly performs electric power feeding to the electric power reception device, a temperature measurement unit that measures the temperature of the electric power transmission unit, and a control unit that controls the electric power transmission unit so that the electric power transmission unit wirelessly performs electric power feeding to the electric power reception device when the temperature measured by the temperature measurement unit at startup is not higher than or lower than a predetermined second temperature threshold higher than the first temperature threshold.