Disclosed is a composition for electrode comprising (i) a positive electrode active material comprising an iron compound and carbon, and (ii) a copolymer (P) prepared by copolymerization of acrylic acid esters and/or methacrylic acid esters, with an α,β-unsaturated nitrile compound. Also disclosed is an electrode comprised of an active material layer made of the composition for electrode, and a collector. This electrode can be produced by mixing the positive electrode active material, the copolymer (P), a solvent and an optional thickener, by a mixer to prepare an electrode composition slurry with solid content of 40-90% by weight, coating a collector with the electrode composition slurry, and then, removing the solvent from the thus-formed coating. Further disclosed a battery provided with the electrode.