PURPOSE: To output only effective data by generating a pulse signal when there is a supply pulse present in a 1st specific time after the start end of the supply pulse, and inhibiting the output of an output data signal during the generation, and repeating and outputting the output data signal only for a 2nd specific time from the pulse signal is ceased.

CONSTITUTION: When a data presence position pulse is supplied, the output terminal 1 of a flip-flop 7 in a pulse generating circuit 3 is inverted to a high level in response to the rise of a clock pulse after the supply point of time and the output of an AND circuit 10 goes up to the high level. Then the output terminal Q of the flip-flop 8 is inverted to a low level in response to the rise of a next clock pulse. The pulse generating circuit 3, therefore, generates a pulse signal having time width corresponding to once cycle of the clock pulse. Then a switch 6 inhibits the output of the output data signal indicating a processing result during the generation period of the pulse signal and repeats and outputs the output data signal indicating the processing result only for the 2nd time after the ceasing of the pulse signal. Consequently, only the effective data can be outputted.