A foreign object detection device in the present disclosure includes: a set sensor coil; and a determination device that detects a foreign object, based on voltage of the set sensor coil. A first sensor coil group in the set sensor coil includes unit sensor coils wound in a first winding direction and unit sensor coils wound in a second winding direction opposite to the first winding direction, these coils wound in the respective directions being electrically connected in series. Each unit sensor coil includes a coil conductor prescribing its external shape. Coil conductors are continuously and electrically connected in series. A part or the whole of the coil conductor forming the unit sensor coil in the first winding direction is a part or the whole of the coil conductor forming the unit sensor coil in the second winding direction.