To realize a frequency divider which can have a frequency division ratio 'natural number/2' by using a simple circuit.

The frequency divider which can have the frequency division ratio 'natural number/2' is simplified by providing a 1st both-edge trigger type flip-flop circuit (11) which can be triggered with both leading and trailing edges of an input signal waveform to operate, a 2nd both-edge trigger type flip-flop circuit (12) which is arranged behind the 1st both-edge trigger type flip-flop circuit and can be triggered with both leading and trailing edges of the input signal waveform to operate, and a composite gate (13) which controls the frequency division ratio of the input signal according to the output signals of the 1st and 2nd both-edge trigger flip-flop circuits and a control signal.