A sensor device has: a sensor unit that outputs a sinusoidal detection signal having an amplitude matching a physical quantity to be detected; a reference signal creator that creates a first sinusoidal reference signal having the same frequency and phase as the detection signal; and a demodulator that multiplies the detection signal by the first reference signal and creates, as a first demodulation signal matching the physical quantity, a signal matching a direct-current component included in a signal resulting from the multiplication. The reference signal creator creates a sinusoidal second reference signal having the same frequency as the detection signal but being out of phase with the detection signal. The demodulator multiplies the detection signal by the second reference signal and creates, as a second demodulation signal matching a noise component superimposed on the detection signal, a signal matching a direct-current component included in a signal resulting from the multiplication.