Abstract: A power supply unit is a power supply device that supplies power to a power reception device using electromagnetic induction. The power supply unit has a power supply coil in which planar coils that are formed by winding respective wire materials around the same point in the same plane are arranged from an inner side to an outer side in the radial direction. The power supply unit supplies alternating currents having a common frequency to respective planar coils, thereby generating a magnetic field for supplying power using electromagnetic induction in the space in which the power reception coil is arranged. A static magnetic field that is generated in the arrangement space in the case where a direct current is fed to planar coils is stronger at a position corresponding to an inner circumference of planar coil.