PURPOSE: To set a frequency division ratio of an asynchronous variable frequency divider circuit to an object value with a simple configuration.

CONSTITUTION: The frequency divider circuit is provided with an asynchronous counter 31M comprising cascade connection of plural D flip-flop circuits FF01-FF05, a detection circuit C00 detecting it when the count of the counter 31M is '2', and a circuit FF00 receiving a detection output of the detection circuit C00 and providing an output of a pulse synchronously with an input signal to the counter 31M for each detection output. The input signal is counted down by the counter 31M and an integer N is set to the counter 31M by each pulse to frequency-divide the pulse frequency into 1/N of the frequency of the input signal.