PURPOSE: To simply and economically form a positive electrode for a secondary cell by forming a high molecular monomer on a substrate and electrolyzation- oxidizing or reducing it into a high molecular layer.

CONSTITUTION: A high molecular monomer is stuck on a substrate as a fixed film, it is immersed in a solution containing an electrolyte not dissolving the monomer and electrolyzation-oxidized or reduced to change the monomer solid film into a high molecular layer. The high molecule thus obtained has the reversible oxidation/reduction characteristic and can be used as the positive electrode of a secondary cell. An optional monomer can be selected, a delicate film with good homogeneity is obtain, and the quantity of a positive electrode active material can be correctly set to the desired quantity in advance. The positive electrode for the secondary cell can be economically formed in a simple process.