Electrostatic interactions between polymers and metal ions at the air-water interface and in resulting LB films were investigated. The polymer was prepared from radical copolymerization of 2-(perfluorooctyl)ethyl monomaleate with triethyleneglycol methyl vinyl ether. The metal ions examined were Na+, Cs+, Mg2+, Fe2+, Al3+, and Fe3+. The surface pressure-area isotherms show that all the monolayers on aqueous metal ions reveal more expanded phases than that on pure water. From the FT-IR (reflection and transmission) spectra, the formation of carboxylate salts and the relative pendent orientation of the polymer in LB film could be estimated. Quantitative analysis of metal ion concentration incorporated into the LB film was carried out by XPS measurement.