A semiconductor integrated circuit device for an electronic control unit includes a drive circuit, a prohibition circuit and a pulse monitor circuit. The drive circuit drives an in-vehicle load according to a driving signal outputted from a microcomputer. The pulse monitor circuit monitors a pulse signal outputted from the microcomputer when the microcomputer is in a normal state. The pulse monitor circuit resets the microcomputer and instructs the prohibition circuit to prohibit the drive circuit from driving the in-vehicle load when it is determined that the microcomputer is in an abnormal state. Further, the pulse monitor circuit instructs the prohibition circuit to permit the drive circuit to drive the in-vehicle load when it is determined that the microcomputer is in the normal state after resetting of the microcomputer.