A battery measuring device includes a temperature measuring unit which measures temperature T1 of a secondary battery, a resistance measuring unit which measures an AC resistance value and a DC pulse resistance value of a first discharging period of the secondary battery at the temperature T1, and an estimating unit in which an electric resistance Re1 and a reaction resistance Rc1 of the secondary battery at the temperature T1 are considered as, Re1=AC resistance value Rc1=DC pulse resistance value of the first discharging period−AC resistance value, and which estimates at least an internal resistance of the secondary battery using the temperature T1, electric resistance Re1 and reaction resistance Rc1.