A secondary battery is provided which has a high energy density, a high capacity, an excellent stability in charge-discharge cycle as well as an excellent safety. The secondary battery comprises at least a positive electrode, a negative electrode and an electrolyte, wherein an active material of at least one of the positive and negative electrodes includes at least one compound selected from the group consisting of radical compounds represented by the formula (1) or the formula (3): ##STR00001## (in the formula (1), X1 and X2 each independently represent a group represented by the formula (3), alkoxyl group, halogen atom, hydroxyl group or cyano group, and R1.about.R8 each independently represent hydrogen atom or alkyl group.) ##STR00002## (in the formula (3), R10 represents alkyl group or substituted or unsubstituted phenyl group.)