A secondary battery state detecting apparatus for detecting a state of a secondary battery installed in a vehicle, comprising: a current detecting unit that detects an electric current flowing to the secondary battery; a voltage detecting unit that detects a voltage of the secondary battery; and a determining unit that determines, in a case where an external device is directly connected to terminals of the secondary battery and the secondary battery is charged or discharged without passing through the current detecting unit, whether or not an irregular charging-discharging has occurred, in accordance with a change in a current value and a voltage value detected by the current detecting unit and the voltage detecting unit, wherein the determining unit determines, in a case where the secondary batteries of the vehicle and another vehicle are connected to each other via a cable in order to rescue an exhausted state of the secondary battery of the vehicle or the other vehicle, whether a blind charging or a blind discharging has occurred in the secondary battery of the vehicle, in accordance with a relationship between a change in the current value and a change in the voltage value detected by the current detecting unit and the voltage detecting unit, the blind charging being an irregular charging in which charging is performed without passing through the current detecting unit, the blind discharging being an irregular discharging in which discharging is performed without passing through the current detecting unit has occurred, and wherein the determining unit determines blind charging or blind discharging depending on whether a value obtained by ΔV-ΔI×Z is positive or negative, where ΔI is a change in an electric current detected by the current detection unit, ΔV is a change in a voltage detected by the voltage detecting unit, and Z is an internal resistance of the secondary battery. a current detecting unit that detects an electric current flowing to the secondary battery; a voltage detecting unit that detects a voltage of the secondary battery; and a determining unit that determines, in a case where an external device is directly connected to terminals of the secondary battery and the secondary battery is charged or discharged without passing through the current detecting unit, whether or not an irregular charging-discharging has occurred, in accordance with a change in a current value and a voltage value detected by the current detecting unit and the voltage detecting unit, wherein the determining unit determines, in a case where the secondary batteries of the vehicle and another vehicle are connected to each other via a cable in order to rescue an exhausted state of the secondary battery of the vehicle or the other vehicle, whether a blind charging or a blind discharging has occurred in the secondary battery of the vehicle, in accordance with a relationship between a change in the current value and a change in the voltage value detected by the current detecting unit and the voltage detecting unit, the blind charging being an irregular charging in which charging is performed without passing through the current detecting unit, the blind discharging being an irregular discharging in which discharging is performed without passing through the current detecting unit has occurred, and wherein the determining unit determines blind charging or blind discharging depending on whether a value obtained by ΔV-ΔI×Z is positive or negative, where ΔI is a change in an electric current detected by the current detection unit, ΔV is a change in a voltage detected by the voltage detecting unit, and Z is an internal resistance of the secondary battery.