To provide a small-sized power supply controller which can inexpensively interrupt the power supply to a load from a battery and can detect the output current of the battery.

A switching circuit 100 for an IGBT 11, which turns on and off the large power supply to a load from a battery 1 by switching the IGBT 11 having a heat interrupting function by means of a drive circuit 12, and at turning on/off of the power supply, detects the overcurrent supplied to the load through the IGBT 11 by means of an overcurrent detecting circuit 13 and feeds back the detecting signal to the drive circuit 12 is constituted and the large power supply to the load from the battery 1 is turned on/off by supplying the power of the battery 1 to the load side via the circuit 100. In addition, a detection section which turns on/off the power supply to the load from the battery and detects the output current of the battery 1 can be reduced in size and cost, by making the detecting section for making the turning on/off of the power supply and the detection of the output current into solid-state form by adding a current detecting circuit 14, which detects a current which is in a fixed ratio relation with the current flowing to the IGBT 11 to the constitution and taking out the detected current via a photocoupler 144.