A secondary battery has a positive electrode principally comprising a lithium-containing complex oxide, a negative electrode principally comprising a carbon material and an organic electrolyte solution, said negative electrode utilizing a mixed binder comprising a polyamic acid and at least one polymer selected from the group consisting of a polyamide resin, polyvinylpyrrolidone and a hydroxyalkylcellulose. The battery has a long cycle life and, at the same time, hardly breaks or bursts even when the battery temperature becomes abnormally high, thereby being highly reliable.