A secondary battery degradation state detecting device that detects a degradation state of a secondary battery, comprising: discharge means for subjecting the secondary battery to a pulse discharge; acquiring means configured to control the discharge means to subject the secondary battery to at least one pulse discharge and configured to acquire a time variation of a voltage value during one of the pulse discharges; calculating means configured to calculate a parameter of a predetermined function having time as a variable by fitting the variation of the voltage value during the one of the pulse discharges acquired by the acquiring means, using the predetermined function; and temperature means configured to detect a temperature of the secondary battery; wherein the calculating means are configured to calculate the parameter of the predetermined function with a resistance value acquired dividing the voltage value during the pulse discharge by a current value the predetermined function is an exponential function having time as a variable; characterized by the secondary battery degradation state detecting device being configured to temperature-correct the resistance value on the basis of the temperature of the secondary battery detected by the temperature means and based on a stored table indicating a variation of the resistance value caused by the temperature of the secondary battery; and the secondary battery degradation state detecting device comprising detecting means configured to detect the degradation state of the secondary battery on the basis of the parameter of the predetermined function calculated by the calculating means, wherein the detecting means are configured to detect the degradation state of the secondary battery on the basis of a coefficient of the exponential function. discharge means for subjecting the secondary battery to a pulse discharge; acquiring means configured to control the discharge means to subject the secondary battery to at least one pulse discharge and configured to acquire a time variation of a voltage value during one of the pulse discharges; calculating means configured to calculate a parameter of a predetermined function having time as a variable by fitting the variation of the voltage value during the one of the pulse discharges acquired by the acquiring means, using the predetermined function; and temperature means configured to detect a temperature of the secondary battery; wherein the calculating means are configured to calculate the parameter of the predetermined function with a resistance value acquired dividing the voltage value during the pulse discharge by a current value the predetermined function is an exponential function having time as a variable; characterized by the secondary battery degradation state detecting device being configured to temperature-correct the resistance value on the basis of the temperature of the secondary battery detected by the temperature means and based on a stored table indicating a variation of the resistance value caused by the temperature of the secondary battery; and the secondary battery degradation state detecting device comprising detecting means configured to detect the degradation state of the secondary battery on the basis of the parameter of the predetermined function calculated by the calculating means, wherein the detecting means are configured to detect the degradation state of the secondary battery on the basis of a coefficient of the exponential function.