We described an extremely rare case of adenoid cystic carcinoma associated with salivary duct cyst in the sublingual gland of a 40-year-old Japanese woman. The tumor was growing from the cyst wall and almost occluded the cyst lumen. The epithelium lining the cyst lumen contained both keratin 19-positive cells and α-smooth muscle actin-positive cells, indicating the cyst being derived from the acinus/intercalated duct of the sublingual gland. Therefore, our case has presented for the first time a direct evidence that adenoid cystic carcinoma arises from acinus/intercalated duct.