PURPOSE: To attain sure count of operating number of times of a contact by counting an off-time of a contact signal from the end of a main contact signal and extending the main contact signal over a period until the count time reaches the setting time.

CONSTITUTION: When a contact signal E composing of a main contact signal A and a chattering signal B is applied, the signal E is inverted (1) into a signal F and fed to a clock input terminal C of an FF circuit 2. The circuit 2 is set when the signal F rises and a set output G is inverted to an H level. Since the output G is fed to an AND gate 5 together with the signal F and a clock pulse CP, the pulse CP is sent as an output H only at the L period after the signal A. The signal H is counted by a counter 6 and its count value is fed to a decoder 7. The decoder 7 generates an output signal I by detecting the coincidence of the H signal generated from a predetermined output terminal of the counter 6. The signal B is ended when the signal I is generated. Thus, the effect of chattering is avoided.