A change in an imaginary part of a complex dielectric constant of an inspection object containing moisture is detected as a change in an oscillation frequency. A sensor device includes an oscillation unit that is formed in a semiconductor integrated circuit and an oscillation frequency detection unit that detects an oscillation frequency of the oscillation unit. The oscillation unit has capacitors that are connected to an inspection object in series and changes the oscillation frequency in accordance with a complex dielectric constant of the inspection object.