PURPOSE: To compensate the effect due to the fluctation of control cycle caused by an external function and to maintain the stability of control, by measuring the control cycle given from a timing device and giving the automatic control to the control constant of a control subject in accordance with the measured control cycle.

CONSTITUTION: Control subjects 9W11 are provided corresponding to processors 2W4, respectively, and the processors 2W4 control periodically the subjects 9W11, respectively by a timing command 12 given from a timing system 1. Timing devices 5W7 are connected to the processors 2W4, respectively, and a real time condition signal 15 is supplied to the system 1 from the processors 2W4. Each of these processors fetches the commmand 12 from the system 12 in the form of an interruption signal and calculates the control gain during the control cycle by using the count value of a timer as a measurement control cycle to secure the automatic change of the control gain of the control cycle. Then the adjustment is secured for a control subject 8 by the system 1 to maintain the stability of control.