To compensate a frequency fluctuation caused by a variation of an RC oscillation circuit, etc., and to realize an accurate operation clock.

There are provided an RC oscillator 1 (10) including resistors and capacitors, a counter (20) counting the number of source oscillation clocks from the RC oscillator 1 (10), a frequency setting register (30) for setting the number of source oscillation clocks corresponding to a required oscillation frequency, and a comparator (40) which compares the count value of the counter (20) with the set value of the frequency setting register (30), and the clocks are outputted according to the comparison result.