The monoclonal antibody against a novel protein, which was induced in the roots of rice seedlings treated with NaCl, was produced. Oryzea sativa L. cv. Annapruna grains were sown on clean sands and grown for 10days and then the seedlings were soaked in 50mM NaCl aqueous solution. In 48hrs of the NaCl treatment, the roots were collected and homogenated with liquid nitrogen and extraction buffer. The homogenate was centrifuged and to the supernatant 75％ ammonium sulfate was added to pre-cipitate proteins. From these proteins a novel protein was purified through DEAE-ion chromatography and FPLC(Phenyl column). This protein appeared as a single band in the native electrophoresis. Using this protein as antigen, monoclonal antibody was produced. Five cell lines that secreted antibodies specifically bound to this protein were constructed.