The present invention provides a wireless power relay device and a wireless power transmission system, which can prevent damage to a relay coil caused by the induction of high voltage by reinforcing the relay coil of a region in which the high voltage is induced among a plurality of relay coils. More specifically, the present invention provides the wireless power relay device, which comprises a plurality of relay coils for relaying power transmission by capturing a magnetic field and transmits power to a predetermined point through the magnetic field among a plurality of points at which the relay coils are arranged, wherein a relay coil located at the predetermined point has a larger impedance value than that of the other relay coils.