A reactance measurement apparatus 10 provided with: a series circuit 30 having a first circuit 31 that includes a first resistor 311, and a second circuit 32 that includes a reactance element; a first voltage generation unit 21 for generating a first alternating-current voltage V1 and impressing the same on the series circuit 30; a second voltage generation unit 22 for generating a second alternating-current voltage V2 that has a prescribed phase difference α relative to the first alternating-current voltage V1; a multiplication unit 41 for multiplying the second alternating-current voltage V2 and a second circuit voltage VL and generating a multiplied voltage VX; a measurement unit 42 for measuring the voltage of a direct-current component DC of the multiplied voltage VX; a phase transition amount calculation unit 431 for calculating a phase transition amount θ on the basis of the relationship between the phase difference α of the second alternating-current voltage V2 relative to the first alternating-cur
