Abstract: The present invention relates to a transformer system and a direct current power supply for obtaining a dc current including a luminous body disposed on the primary side for converting a electric power into a light and a solar cell unit disposed on the secondary side, opposing the luminous body, for receiving light emitted from the luminous body and for converting the light into electric power, thereby constituting a transformer which is further provided with an input control circuit and an output control circuit so as to configure a dc power supply. According to this apparatus, a stable dc current can be obtained without generating the magnetic field and noise problems of typical wound core transformers.