In the coil unit 1A of the power supply device 1, the U-shaped plate 51C constituting the U-shaped terminal 50 is used to electrically connect the print-coil substrates 30, 40. Further, the print-coil substrates 30, 40 constituting the coil unit 1A can be connected to the main circuit substrate 20 also by using the U-shaped terminal 50. Here, the print-coil substrate 30 is connected to the print-coil substrate 40 by using the U-shaped terminal 50, by which soldering for fixing the U-shaped terminal 50 is performed from the lower face side of the print-coil substrate 30. Therefore, as compared with a conventional constitution where soldering is performed from both sides of the stacked print-coil substrates, the print coils can be connected by soldering only from one side face, thus making it possible to reduce the amount of work necessary for connecting the print coils.