A 71-year-old man who was being followed-up for esophagus melanosis in the middle thoracic esophagus for 2 years was found to have a black semipedunculated tumor at the same site. Radical subtotal esophagectomy with 2-field lymph node dissection was performed. Histopathological examination indicated a malignant melanoma (pT1b [SM1], N0, Stage I). Adjuvant chemotherapy with DAC-tam (dacarbazine, nimustine, cisplatin, and tamoxifen) was administrated for a diagnosis of primary cutaneous malignant melanoma. After 2 courses of chemotherapy, no recurrence was observed for 10 months. Combined radical surgery with lymph node dissection and systemic chemotherapy is recommended for primary malignant melanoma of the esophagus with submucosal tumor invasion. This treatment is necessary because of the risk of high local recurrence and distant metastasis based on the malignant potential predicted by histopathological examination.