The present invention suppresses the reduction in transmission efficiency caused by the lateral divergence in position between a power supply side coil and a power receiving side coil in a non-contact electrical supply system. A power supply unit is provided with a power supply side helical coil (33) to which power is supplied. A power reception unit is supplied with a power receiving side helical coil (51) that resonates electromagnetically with the power supply side helical coil (33) to receive the electrical power from the power supply side helical coil (33). The impedance of the power supply unit and the power receiving unit is matched in a position where the central axes (Z1, Z2) of the power supply side helical coil (33) and the power receiving side helical coil (51) are offset from one another. Provided is a non-contact electrical supply system wherein the variations in transmission efficiency from product to product are reduced. The number of windings of the power supply side helical coil (32) and the power receiving side helical coil (51) shall be at least three windings but no more than six windings, preferably at least three windings but no more than five windings.
