A noncontact power supply system includes a power supply device having a primary coil acting as an electromagnetic induction coil for a noncontact power supply system, and a power receiving device having a secondary coil. The primary coil has a primary core and a winding wire. The secondary coil has a secondary core and a winding wire. The primary core includes a base segment, a pair of extension segments, and a pair of opposite segments. The pair of opposite segments are arranged to allow a space to be defined therebetween. The winding wire is wound at least around the pair of opposite segments. The secondary coil is arranged between the pair of opposite segments during power supply. The power receiving device includes a magnetic sheet that is in tight contact with an end surface of the secondary core and has an area larger than that of the end surface.