The corrosion resin-casts and the tissue preparations of the digestive diverticula of the common mussel. Mytilus galloprovincialis were observed. The resin-casts were made of the prepolynierization methyl methacrylate (MercoxCL- 2 R) containing 10 % Mercox MA. The tissue preparations were stained with Azan. The openings of the duct of digestive diverticula were the 3 places on the inner wall of the stomach. Three openings of the ducts, which were orifice, existed in the inner wall of the stomach. The cilium and villus were distributed separately on the inner wall of the main duct. However, only villus was distributed on the inner wall of the secondary duct. All the tubules derived directly from the secondary duct.