An impedance measuring device, comprising: a fuel cell having a plurality of stacked battery cells, a capacitance component, and a resistance component, the capacitance component and the resistance component changing in accordance with a state of the battery cells; a positive output unit configured to be connected to a positive electrode terminal of the fuel cell, the positive output unit outputting an AC signal having a predetermined frequency for measuring an internal impedance of the fuel cell; a negative output unit configured to be connected to a negative electrode terminal of the fuel cell, the negative output unit outputting the AC signal having the predetermined frequency; a detection unit configured to detect an AC potential difference between the positive electrode terminal and a midpoint of the fuel cell; an adjustment unit configured to adjust an amplitude of the AC signal at the positive output unit so as to converge a detection signal indicating the AC potential difference on a predetermined value, the predetermined value bringing about a match between the detection signal indicating the AC potential difference and an AC potential difference between the negative electrode terminal and the midpoint; an in-phase component extraction unit configured to multiply the detection signal indicating the AC potential difference by an in-phase signal, and extract a resistance component of the detection signal indicating the AC potential difference, the in-phase signal being in phase with the AC signal having the predetermined frequency; a calculation unit configured to calculate a positive real axis impedance on the basis of the resistance component and the output signal; an orthogonal component extraction unit configured to multiply the detection signal indicating the AC potential difference by an orthogonal signal, and extract a capacitance component of the detection signal indicating the AC potential difference, a phase of the orthogonal signal being orthogonal to a phase of the AC signal having the predetermined frequency; and a reproduction unit configured to reproduce a vector value of the detection signal indicating the AC potential difference on the basis of the extracted capacitance component and resistance component, wherein the adjustment unit configured to adjust the amplitude of the AC signal at the positive output unit so that the reproduced vector value equals the predetermined value. a fuel cell having a plurality of stacked battery cells, a capacitance component, and a resistance component, the capacitance component and the resistance component changing in accordance with a state of the battery cells; a positive output unit configured to be connected to a positive electrode terminal of the fuel cell, the positive output unit outputting an AC signal having a predetermined frequency for measuring an internal impedance of the fuel cell; a negative output unit configured to be connected to a negative electrode terminal of the fuel cell, the negative output unit outputting the AC signal having the predetermined frequency; a detection unit configured to detect an AC potential difference between the positive electrode terminal and a midpoint of the fuel cell; an adjustment unit configured to adjust an amplitude of the AC signal at the positive output unit so as to converge a detection signal indicating the AC potential difference on a predetermined value, the predetermined value bringing about a match between the detection signal indicating the AC potential difference and an AC potential difference between the negative electrode terminal and the midpoint; an in-phase component extraction unit configured to multiply the detection signal indicating the AC potential difference by an in-phase signal, and extract a resistance component of the detection signal indicating the AC potential difference, the in-phase signal being in phase with the AC signal having the predetermined frequency; a calculation unit configured to calculate a positive real axis impedance on the basis of the resistance component and the output signal; an orthogonal component extraction unit configured to multiply the detection signal indicating the AC potential difference by an orthogonal signal, and extract a capacitance component of the detection signal indicating the AC potential difference, a phase of the orthogonal signal being orthogonal to a phase of the AC signal having the predetermined frequency; and a reproduction unit configured to reproduce a vector value of the detection signal indicating the AC potential difference on the basis of the extracted capacitance component and resistance component, wherein