Disclosed is a polyradical compound which can be used as an electrode active material for at least one of a positive electrode and a negative electrode. The polyradical compound has a repeating unit represented by general formula (1) and is crosslinked using a bifunctional crosslinking agent having two polymerizing groups in the molecule represented by general formula (2), wherein R1 to R3 each independently represent hydrogen or methyl group; R4 to R7 each independently represent C1 to C3 alkyl group; X represents single bond, linear, branched or cyclic C1 to C15 alkylenedioxy group, alkylene group, phenylenedioxy group, phenylene group or structure represented by general formula (3); and R8 to R13 each independently represent hydrogen or methyl group, and k represents an integer of 2 to 5.