A microminiature power converter includes a semiconductor substrate on which a semiconductor integrated circuit is formed, and a thin magnetic induction element. The magnetic induction element includes a magnetic insulating substrate having first and second principal planes and a plurality of through-holes. A coil is formed on a central region of the magnetic insulating substrate, and electrodes are formed on the first and second principal planes at peripheral regions of the magnetic insulating substrate, and electrically connected to the magnetic insulating substrate via respective through-holes. Wiring is formed on the first principal plane in the central region of the magnetic insulating substrate and connected to a capacitor. One end of the wiring is connected to one of the electrode electrodes, and an insulator layer is provided between the wiring and the coil.