PURPOSE: To reduce power consumption while enabling the high-speed operation of a variable frequency division part.

CONSTITUTION: This prescaler is provided with a variable frequency division means 1 composed of plural flip-flops for outputting (n) or (n+1) frequency division output based on first control signals, an expansion means 2 for frequency dividing the output of the variable frequency division means 1 to (m) and outputting N frequency division or (N+1) frequency division output, a feedback means 3 for supplying the first control signals for controlling the output of the flip-flop of the final stage of the variable frequency division means 1 to the variable frequency division means 1 based on the output of the expansion means 2 and second control signals and a control means 4 for controlling a voltage to be supplied to the flip-flop of the final stage of the variable frequency division means 1 based on the output of the expansion means 2, and (n), (m) and N are integers satisfying (n)×(m)=N.