PURPOSE: To stabilize the operation of the monitoring circuit, by counting the number of times of the operation of the program monitoring timer of a monitoring circuit for programs, and stopping a system according to the counted value of the number of times of operation.

CONSTITUTION: When a power source is turned on, a program monitoring timer 1 and a counter 3 are cleared and then triggering is performed by a program at certain intervals of second order to initialize the timer 1. If the program is executed improperly at this time, the triggering is not carried out at said intervals and for this purpose, while the timer 1 is operated to send an input to a trailing counter 3, a one-shot circuit 2 is operated to reset a CPU, starting the program in its initial state. In case of the fault that resetting and program initialization are repeated, the resetting frequency of the timer 1 is counted by the counter 3 and the system is stopped when a prescribed counted value is obtained, thereby reporting the conditions to the outside.