A secondary battery includes a cathode, an anode, and an electrolyte layer including non-aqueous electrolytic solution and a polymer compound. The polymer compound includes a graft copolymer. The graft copolymer includes a block copolymer as a main chain, and includes one or both of a homopolymer and a copolymer as one or more side chains. The block copolymer includes, as polymerization units, vinylidene fluoride and hexafluoropropylene. The homopolymer includes, as a polymerization unit, one selected from the group consisting of vinylidene fluoride, hexafluoropropylene, monomethyl maleate, trifluoroethylene, chlorotrifluoroethylene, acrylic acid, and methacrylic acid. The copolymer includes, as polymerization units, two or more selected from the group consisting of vinylidene fluoride, hexafluoropropylene, monomethyl maleate, trifluoroethylene, chlorotrifluoroethylene, acrylic acid, and methacrylic acid.