The structure of polymeric Langmuir-Blodgett (LB) films was studied by scanning force microscopy (SFM), Fourier transform infrared spectroscopy (FTIR) spectroscopy, and second harmonic generation (SHG) measurements. Polyamic acid alkylamine salt LB films, having an azobenzene pendant unit, were prepared by mixing the polyamic acids with single-chain alkylamines or multichain alkylamines. When the single-chain alkylamine was used, the SFM image of the LB film showed an island-like structure. The formation of the islands was attributed to a self-aggregation of the alkylamines in the LB film. FTIR and SHG measurements suggested that the single-chain alkylamines in the LB film had a poor orientation, and the azobenzene units had a tilt angle of 45.3 degrees from the surface normal. On the other hand, the LB films having multichain alkylamines exhibited a well-ordered orientation. The surface structure was observed uniform and there existed few defects in the SFM images. The multichain alkylamines were oriented approximately perpendicular to the surface plane, and the azobenzene unit had a tilt angle of 39.8 degrees.