PURPOSE: To sense failure of a fuse by emitting an abnormality signal when the input to No.2 level judging circuit has attained the level pulled up by a pullup resistance, and thereby lessening the number of parts used.

CONSTITUTION: Resistance circuits R, R' are parallely connected to the output sides of fuses F1WFn installed in plus side power supply lines l1Wln to form a voltage sensing circuit 1, and a plurality of voltage outputs from this voltage sensing circuit 1 are put into No.1 level judging circuit 2, and when at least one of the voltage outputs to be put in has sunk below the specified level, an abnormality signal shall be emitted. The voltage output taken out of the output side of a fuse Fc in a minus side power supply line lc is put into No.2 level judging circuit NOT3 with the input voltage pulled up by resistance R0, and when this input has attained the level pulled up by pullup resistance R0, an abnormal signal shall be emitted. The allows sensing of failure in the fuses F1WFn, Fc with simple construction.