A semiconductor device is provided which can reduce a parasitic inductor and/or parasitic capacitance added to the wiring that couples spiral inductors and MOS varactors included in a VCO. An LC-tank VCO includes first and second spiral inductors, and first and second MOS varactors. As seen perpendicularly to the semiconductor substrate, the first and second MOS varactors are arranged in a region between the first spiral inductor and the second spiral inductor.