To solve the problem of a conventional DC power supply that the area where any power supply system disconnection, including output path disconnection, electronic substrate pattern damage, and defective connector contact, occurs overheats, resulting in such phenomenon as a resin component melts and deforms and in the worst case, leads to the possibility of fire due to disconnection of the system.

If the potential difference between the output part of a DC power supply and the input part of a load device reaches an abnormal level, it is judged that any abnormality has occurred with the power supply path in the section, and a power supply output is stopped without delay, to prevent abnormal overheating and fire.