PURPOSE: To provide an abnormal current detecting circuit which can surely detect all of abnormal currents under load with simple arrangement.

CONSTITUTION: This abnormal current detecting circuit is provided with a current detecting resistor 3a for interconnecting the ground line B of a power supply 1 and the ground line A of a load 2 and a first and a second resistor 3b, 3c connected in series between the ground line A and the negative voltage terminal 1b of the power supply 1. Further, it is provided with a detector circuit 3 having a comparator circuit 3d for generating a detection signal when the voltage between the first resistor 3b and the resistor 3c is used for a reference voltage and a voltage in the ground line B becomes lower than the reference voltage and a control circuit 4 for generating a drive signal for driving the load 2 and at the same time interrupting the generation of an electric power from the power supply 1 when the detection signal is received from the comparator circuit 3d while the drive signal is not generated.