Four copper phthalocyanines without substituent (CuPc) and with chlorine (CuPc-Cl), hydroxymethyl (CuPc-CH2OH), and phthalimidomethyl substituents (CuPc-CH2N[C(O)(])2Ph) were plasma-polymerized to obtain amorphous and thin films having the extended pi-electron system. The chemical composition of the plasma polymer films was discussed from the data of the electronic spectra, IR spectra, and XPS spectra. The application of the plasma polymer films was discussed with regard to the NO2 sensitivity, the NO2 selectivity, the response time, and the reversibility. Plasma polymerization of CuPc, CuPc-Cl, CuPc-CH2OH, and CuPc-CH2OH gives amorphous films having the extended pi-electron system. In the plasma polymerization process, a part of the extended pi-electron system is broken down. The CH2OH and CuPc-CH2N[C(O)](2)Ph substituents contribute to minimizing the degradation. The Cu atoms liberated from the chelation in the plasma polymerization process exist as CuO in the deposited films. The plasma polymer films of CuPc-CH2OH and CuPc-CH2N[C(O)](2)Ph show good sensitivity to NO2 molecules. With regard to the sensitivity, the selectivity, the response time and the reversibility, the plasma polymer films are applicable materials to the NO2 sensor device.