To provide a variable capacitance device capable of obtaining three or more capacitance values as well as reducing the size of the device and signal loss, and a drive voltage control circuit.

A drive capacitance C1 of a variable capacitance element 2 changes according to drive voltage Vd output from a drive voltage control circuit 31. The drive voltage control circuit 31 comprises a comparator 32 which compares a detection value and a target value of the drive capacitance C1; and a drive voltage generating circuit 34 which generates a drive voltage Vd according to the comparison result of the comparator 32. A current output type level conversion circuit of the drive voltage generating circuit 34 causes a source current or a sink current to flow to a smoothing capacitance according to the comparison result of the comparator 32 and steps up or down the drive voltage Vd. To the smoothing capacitance, an auxiliary capacitance which is connectable or blockable with a switch is connected in parallel.