Morphological characteristics of hemocyte in pontoniine shrimp Conchodytes nipponensis were examind. Only a single type of hemocyte, eosinophilic granulocyte, was observed in the hemolymph of the shrimp. This cell was round to spindle-shaped one and characterized by the presence of two types of eosinophilic granules, one was small (round； ≦0.5 μm in diameter) and the other was large (round to oval； ≦1.0 μm in diameter). The former was strongly and the latter was weakly eosinophilic. This is the first report on the monohemocytic decapod.