The corrosion resin-casts and the tissue preparations (Azan staining) of the digestive diverticula in a sea hare, Aplysia (Varria) kurodai, were observed. The digestive diverticula were situated on the ventral side of stomach. Three ducts arose from the proximity of the style sac: one from the right side and two from the left side of the style sac. Each duct ramified. Each tubule extended to the side wall or end of the duct, and was branching out. From the results of the observations, we concluded that the digestive diverticula in a sea hare (Opisthobranchia : Aplysiomorpha) have the structure similar to those in Prosobranchia (Vetigastropoda).