Monoclonal antibody against HBV pre-S2 peptide was generated. Six clones among 70 hybridomas which were survived in HAT media produced anti pre-S2 antibody. All six clones has been identified to produce IgM-type monoclonal antibody which has kappa light chain after ELISA subtyping analysis. After purification of IgM monoclonal antibody, heavy and light chain of immunoglobulin has been identified whose molecular weights are 79KD and 26.5KD, respectively. These pre-S2 antibodies were confirmed using immunoblotting techniques. IgM type pre-S2 monoclonal antibody were bound to 55 amino acid pre-S2 antigen whose M.W. is 55KD.