PURPOSE: To provide a short-circuit protective circuit for detecting an overcurrent caused by short-circuit of an apparatus using a DC power and limiting the overcurrent to a certain value or less and turning off a power supply if necessary and a method of resetting the power source to the apparatus using the DC power.

CONSTITUTION: When detection of overcurrent is received by a photocoupler 2 of a short-circuit protective circuit, a control apparatus 7 outputs an off command to a photocoupler 3 if necessary, and a power source to a demand system is turned off. Also, for a demand system such as a microcomputer control unit, after turning off the power supply, a certain time elapses and then the power supply is turned on and thereby a power source reset to the demand system is performed.