The ultrastructure of the tentacular pigment cells and the origin of the pigment granules in the Chinese mystery snail, Cipangopaludina chinensis malleata Reeve, are studied with electron microscope. Tentacular pigment cells of the Enail are the melanophores which contain electron dense melanosomes(melanin pigment granules) . Melanophores are distributed among the connective tissues but otter kind of dermal chromatephores are not observed. The epidermal melanin units are observed in the epithelial tissues of the tentacles. Among the several kinds of epithelial cells, only the epithelial supporting cells contain these pigment granules. Synthesis of the pigment materials is from the rough ER and pigment granules are finally being packaged and released by the Golgi complexes but limiting membrane of these granules are presumed to be originated from the smooth ER.