A signal analysis apparatus includes a first frequency conversion unit 10 that generates an intermediate frequency signal SIF2 and a second spurious signal SSP2 from a measured signal SRF of a frequency fRF (center frequency fc), and a second frequency conversion unit 25 that converts the intermediate frequency signal SIF2 and the second spurious signal SSP2 into an intermediate frequency signal SIF2′ of a frequency fIF2′ and a second spurious signal SSP2′ of a frequency fSP2′ by performing frequency shift of the intermediate frequency signal SIF2 and the second spurious signal SSP2 by a frequency shift amount Δf, in which the frequency shift amount Δf is a value that does not establish a relationship of −W/2≤fSP2′−fIF2′≤+W/2.