Primary malignant melanoma of the anorectal region is a relatively rare entity and the prognosis is very poor. We experienced a case of malignant melanoma of the region. A 65-year-old man was seen at the hospital because of anal pain lasting for about one month and admitted with a diagnosis of the malignant melanoma. Preoperative imagings revealed no other lesions such as lymph nodes metastasis and no inguinal lymph node was palpated. So an abdomino-perineal resection with D 2 dissection was performed, followed by DAV (dacar-bazine, nimustatine, vincristine) therapy as adjuvant chemotherapy. The resected specimen revealed two black tumors with the sizes of 3.5×3.0cm and 1.7×1.1cm at the anorectal junction. At present, three months after the operation, no findings suggesting the recurrence have been observed and noticed. It is suggested that early discovery and establishment of the standard surgical therapy would promise good prognosis to this disease.