A polymer Langmuir-Blodgett (LB) film containing a large porphyrin chromophore was prepared from the copolymer (pDDA-Por) consisting of N-dodecylacrylamide (DDA) and N-[(N'-aminopropyl)pyridyltriphenylporphyriante(Zn(II))]acrylamide (Por). The spreading behavior of the copolymer monolayer at the air-water interface was investigated by measuring the surface pressure (pi)-surface area (A) isotherm. The isotherm indicates that pDDA-Por forms a stable, condensed monolayer with a steep rise in rr, and has a high collapse pressure of 52 mN/m. The monolayer can be transferred onto hydrophobic solid supports giving a typical Y-type LB film. A flat orientation of the porphyrin ring in the LB films is discussed from the absorption dichroism measurement.