While a microcomputer is executing a self-diagnosis (A), second diagnosis pulse output means of a B-system microcomputer is not used utterly. Further, during this time, the B-system microcomputer 100B does not execute a processing relating to at least the self-diagnosis (A) utterly. By shifting the timings for the A-system and the B-system to output the diagnosis pulses, independencies can be secured between respective diagnosis processing (self-diagnoses (A) and (B)). Thus, the independencies between the A-system and the B-system can be verified briefly by the self-diagnosis (A) on the A-system side. Further, first diagnosis pulse group are outputted parallel and simultaneously from first diagnosis pulse output means. Thus, since cyclic control is not required for respective external input devices, it can be done to verify the independencies between the A-system and the B-system within a short period of time.