An ultra slim power supply device for supplying power to an electric vehicle in a contactless manner includes at least one power supply track buried in a road. Each power supply track includes a plate-shaped magnetic core extending along the road, a plate or strip shaped magnetic field generator arranged above the magnetic core through which an alternating current is supplied to generate a magnetic field, a plate or strip shaped insulating body positioned between the magnetic core and the magnetic field generator to isolate them from each other, and a housing for enclosing the magnetic core, the magnetic field generator and the insulating body.