A wireless power transfer system comprising a first coil device , and a second coil device , wherein the first coil device faces the second coil device in a facing direction (Z), and is configured to wirelessly transmit or receive power to and from the second coil device , the first coil device comprising: a first coil portion including a conductive wire wound around a ferrite plate ; and a first auxiliary magnetic member (30, 30a - 30d, 50A-50F, 60) provided adjacent to the first coil portion in a first direction (Y) orthogonal to the facing direction (Z), wherein a space (S) is provided between the first auxiliary magnetic member (30 30a - 30d, 50A-50F, 60) and the first coil portion in the first direction (Y), the second coil device comprising a second coil portion , wherein the first auxiliary magnetic member (30, 30a-30d, 50A-50F, 60) has a facing surface configured to be closer to the second coil device in the facing direction (Z) with increasing distance in the first direction (Y) from the first coil portion wherein, in case a misalignment occurs between the first coil device and the second coil device in the first direction (Y), the magnetic flux (F) is directed to the second coil portion via the first auxiliary magnetic member (30, 30a-30d, 50A-50F, 60), and in case no misalignment occurs between the first coil device and the second coil device in the first direction (Y), the magnetic flux is easily intensively directed to a path from the first coil portion to the second coil portion while not passing through the first auxiliary magnetic member (30, 30a-30d, 50A-50F, 60), the facing surface becomes higher outward with respect to the first coil portion , wherein a highest distal end of the facing surface corresponds to an apex portion . a first coil portion including a conductive wire wound around a ferrite plate ; and a first auxiliary magnetic member (30, 30a - 30d, 50A-50F, 60) provided adjacent to the first coil portion in a first direction (Y) orthogonal to the facing direction (Z), wherein a space (S) is provided between the first auxiliary magnetic member (30 30a - 30d, 50A-50F, 60) and the first coil portion in the first direction (Y), the second coil device comprising a second coil portion , wherein the first auxiliary magnetic member (30, 30a-30d, 50A-50F, 60) has a facing surface configured to be closer to the second coil device in the facing direction (Z) with increasing distance in the first direction (Y) from the first coil portion wherein, in case a misalignment occurs between the first coil device and the second coil device in the first direction (Y), the magnetic flux (F) is directed to the second coil portion via the first auxiliary magnetic member (30, 30a-30d, 50A-50F, 60), and in case no misalignment occurs between the first coil device and the second coil device in the first direction (Y), the magnetic flux is easily intensively directed to a path from the first coil portion to the second coil portion while not passing through the first auxiliary magnetic member (30, 30a-30d, 50A-50F, 60), the facing surface becomes higher outward with respect to the first coil portion , wherein a highest distal end of the facing surface corresponds to an apex portion . <EOS>