The corrosion resin-casts and the tissue preparations of the digestive diverticula of the Japanese hard clam, Meretrix lusoria were observed. The resin-casts were made of the prepolymerization methyl methacrylate (MercoxCL-2R) containing 10 % Mercox MA. The tissue preparations were stained with Azan. The digestive diverticula developed in the circumference of stomach except for the dorsal side. The origins of the multiple ducts located at 3 embayments of the stomach. Internal wall of the duct was uniformly covered with the cilium from the origin to the apex. Each tubule extended at the end of the duct. The tubule had the darkly staining cell at the crypt with the long cilium.