The monolayer behaviors of poly(N-alkylmethacrylamides) with various pendant substituents, octyl (POMA), dodecyl (PDDMA), tetradecyl (PTDMA), hexadecyl (PHDMA), or octadecyl (PODMA), on the water surface and the properties of the Langmuir-Blodgett (LB) films were investigated. Among those polymers, PTDMA formed the most stable condensed monolayer. The PTDMA monolayer can be transferred successively onto solid supports such as quartz, glass, and silicon slide, giving Y-type uniform polymer LB films. It was found that PTDMA LB film could be effectively decomposed by deep UV irradiation and produced directly a positive fine pattern with high resolution without any development process. The sensitivity of the PTDMA LB film was remarkably enhanced with decreasing number of layers. This lithographic property of the LB film is expected to be applicable to a new type of positive photoresist for a deep UV excimer laser.