An internal resistance measurement device for a stacked battery , comprising: an AC power supply part configured to output an AC current to an internal resistance measurement object comprising a stacked battery made of a plurality of stacked power generating elements by being connected to the internal resistance measurement object; and a resistance calculating part ; the internal resistance measurement device being characterised by further comprising: an AC adjusting part configured to adjust an AC current so that a positive electrode AC potential difference, being a potential difference obtained by subtracting potential in a middle portion from potential in a portion connected to a load device on the positive electrode side of the internal resistance measurement object, matches a negative electrode AC potential difference, being a potential difference obtained by subtracting potential in the middle portion from potential in a portion connected to the load device on the negative electrode side of the internal resistance measurement object, and result in a same AC potential difference for the positive electrode AC potential difference and the negative electrode AC potential difference; wherein the resistance calculating part is configured to calculate the internal resistance of the stacked battery based on the adjusted AC current and the AC potential difference. an AC power supply part configured to output an AC current to an internal resistance measurement object comprising a stacked battery made of a plurality of stacked power generating elements by being connected to the internal resistance measurement object; and a resistance calculating part ; the internal resistance measurement device being characterised by further comprising: an AC adjusting part configured to adjust an AC current so that a positive electrode AC potential difference, being a potential difference obtained by subtracting potential in a middle portion from potential in a portion connected to a load device on the positive electrode side of the internal resistance measurement object, matches a negative electrode AC potential difference, being a potential difference obtained by subtracting potential in the middle portion from potential in a portion connected to the load device on the negative electrode side of the internal resistance measurement object, and result in a same AC potential difference for the positive electrode AC potential difference and the negative electrode AC potential difference; wherein the resistance calculating part is configured to calculate the internal resistance of the stacked battery based on the adjusted AC current and the AC potential difference. an AC adjusting part configured to adjust an AC current so that a positive electrode AC potential difference, being a potential difference obtained by subtracting potential in a middle portion from potential in a portion connected to a load device on the positive electrode side of the internal resistance measurement object, matches a negative electrode AC potential difference, being a potential difference obtained by subtracting potential in the middle portion from potential in a portion connected to the load device on the negative electrode side of the internal resistance measurement object, and result in a same AC potential difference for the positive electrode AC potential difference and the negative electrode AC potential difference; wherein the resistance calculating part is configured to calculate the internal resistance of the stacked battery based on the adjusted AC current and the AC potential difference. <EOS>