Abstract: A device is provided to prevent erroneous operation of an object to be controlled connected to the controller if the clock is interrupted. When a clock monitoring unit (15) detects that no clock pulse signal (CL) is generated from a clock generating unit (14) in a controller (10), a D flip-flop (13) is forcibly turned off, so that no drive signal is given to the actuator that is the object to be controlled. Moreover, a clock monitoring unit (42) in a controller (40) detects whether a clock pulse signal (CK1) is being sent from a controller of the preceding stage or not. When the clock pulse signal (CK1) is being received, the clock monitoring unit (42) sends the clock pulse signal (CK1) to the actuator that is the object to be controlled via a data processing unit (44). When the clock pulse signal (CK1) is not detected, a clock pulse signal (CK2) of a self clock generating unit (41) is sent to the actuator that is the object to be controlled via the data processing unit (44).