A power transmission device includes power transmission coils arranged in a line in a plane, a power transmission circuit connected to the power transmission coils and supplying AC power, and a control circuit controlling a connection state between the power transmission circuit and each power transmission coil. The length of each power transmission coil in the array direction is shorter than that of the power receiving coil in that direction, the length thereof in a direction perpendicular to the array direction in the plane is longer than that of the power receiving coil in that direction, and the control circuit selects adjacent power transmission coils whose number is fixed based on the relative position of the power receiving coil with respect to the power transmission coils and switches the above connection state such that the AC power is supplied to the selected power transmission coils.