PURPOSE: To protect a power supply against short circuit and to make possible to detect failure of load prior to turn ON of DC power supply by providing a load state detecting section, a switching circuit section, and a control section therefor.

CONSTITUTION: The protective circuit for DC power supply comprises a state detecting section 4 for detecting short circuit or disconnection of a load 2 and outputting a short circuit signal 62 or a no-load signal 61, a circuit section 3 for switching connection of the load 2 between a DC power supply and the state detecting section 4, and a control section 5 for determining the operation of the switching circuit section 3 based on the short circuit signal 62, the no-load signal 61, and an external control signal 63.