The authors observed the degree of alveolar bone resorption on the intraoral roentgenogram of 105 patients who were affected by periodontal disease, and following results were obtained. That is, the alveolar bone resorption due to the periodontal disease showed increased tendency as aging, and severe degree on the mandible in comparison with the maxilla, and revealed sere destruction on the area of mandibular incisors and maxillary molars.