ABNORMALITY MONITORING CIRCUIT OF ECU

PROBLEM TO BE SOLVED: To provide an ECU monitoring circuit which does not output a reset signal before the end of BIST and does not spoil performance of a system.SOLUTION: An abnormality monitoring circuit of an ECU 1 includes a microcomputer 5, a reset circuit 3 for resetting the microcomputer 5, a monitoring circuit 4 for monitoring the operation of the microcomputer 5, and an output circuit 6 for driving an external actuator. The monitoring circuit 4 includes: abnormality determination signal output means 41 which outputs an abnormality determination signal 10 to the output circuit 6 when being not able to confirm a normality monitoring signal 12 of the microcomputer 5 by an abnormality determination time T1; and reset determination signal output means 42 which outputs a reset determination signal 11 to the reset circuit 3 when being not able to confirm the normality monitoring signal 12 of the microcomputer 5 by a reset determination time T3 set later than a BIST completion time T2 of the microcomputer 5 and the abnormality determination time T1.