PURPOSE: To perform reliable normal operation of a main CPU by providing a means to output a reset signal for an engine stop during detection of an engine stall, a means to decide that abnormality occurs to a sub CPU during non-occurrence of an engine stall, and a means to output a reset signal for emergency when it is decided that abnormality occurs.

CONSTITUTION: It is decided by means of a reference signal from a crank angle sensor whether or not the number of revolutions is zero. When it is zero, it is decided that an engine stall occurs, and a reset signal is outputted through an AND circuit 13 to a sub CPU 12 to effect reset. Meanwhile, when it is decided that an engine is run and when a program run signal (P-RUN) from the sub CPU 12 is inverted each time a reference signal is inputted, it is decided that the sub CPU 12 is normal. When the P-RUN signal is maintained at a high and a low level despite of the presence or absence of the input of the reference signal, it is decided that abnormality occurs to the sub CPU 12, a reset output is outputted through the AND circuit 13, and operation of the sub CPU 12 is reset. In this case, data of an RAM is cleared.