A power supply voltage control apparatus including an input signal generation circuit of wide uses or a small-sized monitor circuit of a novel configuration, and a semiconductor circuit and a method for driving the same, having a semiconductor circuit 11, an input signal generation circuit 12 able to change the phase difference i of a reference signal outφi and an input signal outφ0 in accordance with a control signal Si when generating the two signals from a clock, a monitor circuit 13 having a characteristic between a power supply voltage and delay the same as that of a critical path of the semiconductor circuit 11, propagating the input signal outφ0, and outputting a delayed signal outφ0′ to be delayed exactly by a time equivalent to a delay of the critical path (or smaller by a constant ratio), a delay detection circuit 14 for detecting a delay of the delayed signal outφ0′ relative to the reference signal outφi, and a power supply voltage control circuit 15 for controlling a power supply voltage VDD supplied to the semiconductor device 11 and the monitor circuit 13 based on the detection result.