A semiconductor device 2 has a plurality of elements. It also has an F-V table storing unit for low voltage threshold cells 31 for storing an F-V table TB11 of an oscillation frequency f1 relying on the plurality of elements and a power supply voltage EV to be supplied to the plurality of elements. It has a process sensor block 12 having at least one of the plurality of elements, for monitoring the oscillation frequency f1 relying on at least one element. It further has a selector 33 for setting the power supply voltage EV associated with the oscillation frequency f1, as the supply voltage to be supplied to the semiconductor device 2 by selecting according to the F-V table TB11. The F-V table TB11 is obtained by mutually relating the combinations of random number models ξn between an F-ξ table TB20 and an ξ-V table TB30.