An intermittent reception waiting time period is roughly counted by counting low frequency clocks using a low frequency clock counter and a remainder of the intermittent reception waiting time period which cannot be counted with a time resolution of the low frequency clocks is counted by counting high frequency clock pulses using a high frequency clock counter with a high time resolution. Outputs of the high frequency clocks are prohibited while the intermittent reception waiting time period is counted by the low frequency clock counter. As a result, accurate start timing of an intermittent reception can be set with reduced power consumption caused by prohibiting the outputs of the high frequency clock pulses.