The sudden generation of heat being frequently caused in the case of the overcharge of a lithium secondary cell which have a positive electrode comprising a composite metal oxide of lithium and cobalt or a composite metal oxide of lithium and nickel, a negative electrode comprising metallic lithium, a lithium alloy or a material capable of occluding and releasing lithium, and a nonaqueous electrolyte solution comprising a nonaqueous solvent and an electrolyte dissolved therein can be efficiently prevented by the addition, to the nonaqueous electrolyte solution, of an organic compound which, when the lithium secondary cell is overcharged, decomposes into a decomposition product capable of dissolving out the cobalt or nickel contained in the positive electrode and depositing it ion the negative electrode (for example, a tert-alkylbenzene derivative).