A device for detecting the presence of a parasitic metal object on a reception surface of a device for recharging a user apparatus for an automotive vehicle, the device including an antenna of the emitting coil type and: at least two identical passive detection coils, situated between the emitting coil and the reception surface; a determiner for determining the quality factor across the terminals of the two coils, and of the emitting coil; a controller; a storage device for storing the quality factors at predetermined instances; a calculator for calculating ratios between the stored quality factors, or between values of the quality factors stored at different predetermined instances; a comparator for comparing between the ratios in order to detect the presence of an interfering metal object on the reception surface.