PURPOSE: To provide a counter able to make counting with high accuracy even when a period of an input signal is short or long with respect to the counter device used to count the input signal whose period is equal to or shorter than that of a system clock with high accuracy.

CONSTITUTION: This counter device is a device receiving at least one input signal S and whose counts is increased/decreased according to a change in the input signal S and is made up of an asynchronous 1st counter 1 counting the member of changes in the input signal S, a synchronous 2nd counter 2 operated synchronously with a clock CL, and a control means 3 allowing the 2nd counter 2 to count a value in response to the count of the 1st counter 1 synchronously with the clock CL and resetting the 1st counter.