A secondary battery state detecting device detecting a state of a secondary battery, comprising: a measurement unit (11, 12) configured to measure a current value of a current flowing at the secondary battery and a voltage value of a voltage generated at the secondary battery by the current in a predetermined frequency; an optimization unit configured to optimize element constants of an equivalent circuit model of the secondary battery based on the voltage value and the current value measured by the measurement unit (11, 12); characterized in that the secondary battery state detecting device further comprises: an identification unit configured to identify a kind of the secondary battery with reference to the element constants of the equivalent circuit model which are optimized by the optimization unit; a storage unit configured to store detection formulas which detect the state of the secondary battery based on the element constants of the equivalent circuit model by each kind of the secondary battery; an acquisition unit configured to acquire the detection formula corresponding to the kind identified by the identification unit from the storage unit; and a detection unit configured to detect the state of the secondary battery by applying the element constants to the detection formula acquired by the acquisition unit. a measurement unit (11, 12) configured to measure a current value of a current flowing at the secondary battery and a voltage value of a voltage generated at the secondary battery by the current in a predetermined frequency; an optimization unit configured to optimize element constants of an equivalent circuit model of the secondary battery based on the voltage value and the current value measured by the measurement unit (11, 12); characterized in that the secondary battery state detecting device further comprises: an identification unit configured to identify a kind of the secondary battery with reference to the element constants of the equivalent circuit model which are optimized by the optimization unit; a storage unit configured to store detection formulas which detect the state of the secondary battery based on the element constants of the equivalent circuit model by each kind of the secondary battery; an acquisition unit configured to acquire the detection formula corresponding to the kind identified by the identification unit from the storage unit; and a detection unit configured to detect the state of the secondary battery by applying the element constants to the detection formula acquired by the acquisition unit. an identification unit configured to identify a kind of the secondary battery with reference to the element constants of the equivalent circuit model which are optimized by the optimization unit; a storage unit configured to store detection formulas which detect the state of the secondary battery based on the element constants of the equivalent circuit model by each kind of the secondary battery; an acquisition unit configured to acquire the detection formula corresponding to the kind identified by the identification unit from the storage unit; and a detection unit configured to detect the state of the secondary battery by applying the element constants to the detection formula acquired by the acquisition unit.