Based on a vehicle speed Vv, a vehicle moving amount cvp is calculated from cvp=∫Vv·dt. From the Pythagorean theorem, expressions y2+x2=ra2 and y2+(cb−x)2=cvp2 are held. From these two expressions, an ECU of a non-contact power transmission system obtains x and y. In the expressions, y is a distance in a horizontal direction from a power transmission coil, x is a distance in a vertical direction from the power transmission coil, and ra is a distance from the power transmission coil at a two-dimensional current position and is obtained in advance from a correspondence relation between the distance and the intensity of a power transmitted from the power transmission coil.