To obtain a method for quickly and accurately executing multiplication and division of plural variable frequencies, and a compact circuit to be used for the method.

A frequency multiplying circuit is provided with a first input gate 1 for a first input pulse column, a second input gate 2 for a second input pulse column, and a first control gate 6. Also, this circuit is provided with a control circuit 3 for controlling the first input gate 1 to be connected with a counter 3 in a time T/2 period in a first phase, and the second input gate to be connected with an output in a first sequence period (t) in a second phase, and a clock circuit 5 connected through the control gate 6 to the counter 3. Thus, the first sequence period (t) can be made proportional to frequencies f1 of a first input pulse string appearing at the first input gate 1.