Four monoclonal antibodies (mAbs) were generated by immunizing BALB/C mice with recombinant nucleocapsid protein (N) of Nipah virus (NiV) and Hendra virus (HeV) expressed in E. coli. Two mAbs each were obtained for the HeV N and NiV N, respectively. All four mAbs displayed specific reactivity with the recombinant N proteins of both viruses by western blot, which was further confirmed by immunofluorescent antibody assay using fixed insect cells infected with recombinant baculoviruses expressing either the HeV or NiV N protein. Epitope mapping using a 12-mer random peptide phage display library revealed two linear antigenic sites of the henipavirus N proteins, KLxR (aa 17-20) and FKREM (aa 446-450), which have not been reported previously. Two of the mAbs were able to specifically recognize HeV antigens by immunohistochemical staining of lung tissue sections of a horse experimentally infected with HeV. These reagents will be a useful addition to the collection of tools essential for further research and improvement in diagnosis of henipaviruses.