To include a pulse counting unit, a pulse timing unit, an overflow detection unit that holds a detected matter in an overflow register, a capture unit that holds an output of the pulse counting unit in a pulse counting register and holds an output of the pulse timing unit in a pulse timing register, and a computation unit (frequency calculation unit) that reads the pulse counting register, the pulse timing register, and the overflow register to calculate a frequency computation value, and when the pulse timing unit has overflowed, the computation unit adds a predetermined constant acquired by a period of a capture clock a period of a timing clock to pulse timing data at the previous interrupt to obtain pulse timing data acquired by a period of time from the last pulse edge a period of the timing clock.