The authors have observed a case of adenold cystic carcinoma occured in molar portion of the left mandible in 59-year old woman. The results are as follows: 1. Roentgenographic findings revealed pathological fracture of the left mandibular body. 2. The patient complained of burning sensation of tongue and facial dull pain. 3. Microscopically, in the portion of glandular arrangoment of tumor cells, the mucinous materials were contained, and the mitotic figures of tumor cells did not appear in this case, and the stromal connective tissue revealed hyaline degeneration and myxomatous degeneration. 4. The tumor cells were infiltrated not only perinoural lymphatics, but also perineurum and intraneura tissue.