A positive electrode for a battery includes a positive active material, a conductive agent, and a copolymer. The copolymer includes a constituent unit (a) represented by the following general formula (1) and a constituent unit (b) represented by the following general formula (2): (wherein R1, R2, R3, R5, R6, R7 and R9 are the same or different and denote a hydrogen atom, a methyl group or an ethyl group, R4 denotes a hydrocarbon group having 8 to 30 carbon atoms, R8 denotes a linear or branched alkylene group having 2 to 4 carbon atoms, X1 and X2 denote an oxygen atom or NH, and p denotes a number of 1 to 50).