A cell control device configured to perform the steps of: determining a limit value for a load, ΔVlimit, which is the limit value that is allowed within a certain time for a difference between a closed circuit voltage, CCV, and an open circuit voltage, OCV, of a secondary cell, using a ΔVlimit database, in which a relationship between a state of charge, SOC, and a temperature, T, of the secondary cell and the limit value for the load, ΔVlimit, is recorded, or determining a limit value for a current, I, of the secondary cell, Ilimit, which is the limit value for the current of the secondary cell that is allowed within a certain time, using an Ilimit database, in which a relationship between the state of charge, SOC, and the temperature, T, of the secondary cell and the limit value for the current, Ilimit, is recorded, determining at least one of an upper limit voltage, Vmax, and a lower limit voltage, Vmin, of the secondary cell by using a cell parameter database, in which a relationship between the state of charge, SOC, the temperature, T, and the current, I, of the secondary cell and at least one of the upper limit voltage, Vmax, and the lower limit voltage, Vmin, of the secondary cell is recorded, calculating a cell protection allowable current to protect the secondary cell based on at least one of the upper limit voltage, Vmax, and the lower limit voltage, Vmin, together with the open circuit voltage, OCV, of the secondary cell and a first resistance, R1, of the secondary cell, calculating a ΔV effective value relating to a temporal change of the difference between the CCV and the OCV or an I effective value relating to a temporal change of the current value, representing a magnitude of a present load of the secondary cell, calculating a restriction rate, k, for the allowable current based on the ΔVlimit or the Ilimit and the ΔV effective value or the I effective value, wherein the restriction rate, k, is changed in accordance with the ΔV effective value or the I effective value, and calculating an allowable current of the secondary cell by multiplying the restriction rate, k, and the cell protection allowable current. determining a limit value for a load, ΔVlimit, which is the limit value that is allowed within a certain time for a difference between a closed circuit voltage, CCV, and an open circuit voltage, OCV, of a secondary cell, using a ΔVlimit database, in which a relationship between a state of charge, SOC, and a temperature, T, of the secondary cell and the limit value for the load, ΔVlimit, is recorded, or determining a limit value for a current, I, of the secondary cell, Ilimit, which is the limit value for the current of the secondary cell that is allowed within a certain time, using an Ilimit database, in which a relationship between the state of charge, SOC, and the temperature, T, of the secondary cell and the limit value for the current, Ilimit, is recorded, determining at least one of an upper limit voltage, Vmax, and a lower limit voltage, Vmin, of the secondary cell by using a cell parameter database, in which a relationship between the state of charge, SOC, the temperature, T, and the current, I, of the secondary cell and at least one of the upper limit voltage, Vmax, and the lower limit voltage, Vmin, of the secondary cell is recorded, calculating a cell protection allowable current to protect the secondary cell based on at least one of the upper limit voltage, Vmax, and the lower limit voltage, Vmin, together with the open circuit voltage, OCV, of the secondary cell and a first resistance, R1, of the secondary cell, calculating a ΔV effective value relating to a temporal change of the difference between the CCV and the OCV or an I effective value relating to a temporal change of the current value, representing a magnitude of a present load of the secondary cell, calculating a restriction rate, k, for the allowable current based on the ΔVlimit or the Ilimit and the ΔV effective value or the I effective value, wherein the restriction rate, k, is changed in accordance with the ΔV effective value or the I effective value, and calculating an allowable current of the secondary cell by multiplying the restriction rate, k, and the cell protection allowable current.