In a lithium secondary cell having a negative electrode, a positive electrode and, arranged between the electrodes, a polymer electrolyte layer, the internal resistance of the cell and the interfacial resistance between the electrode and the polymer electrolyte can be reduced by incorporating into the electrode, in advance, a polymer electrolyte precursor solution in a manner such that the electrode has a higher content of the precursor monomer and/or an oligomer thereof than that in the polymer electrolyte layer formed on the electrode.