The Neodolichomitra robusta(Broth．)Nog．is a peculiar species in East Asia．Chromosome number of mitotic metaphase of stem tip cells in gametophyte is n＝5．The karyotype，K(n)＝5＝4m十1sm，or K(n)＝5＝4v+1J，is 2A type．The result is reported for the first time．