Angiosarcoma is a rare malignant tumor of endothelial origin. It is an aggressive neoplasm with early metastasis and poor prognosis and accounts for approximately 2% of all soft tissue sarcomas. Primary tumors arising in the oral cavity account for only 1% of all angiosarcomas. Here, we report a rare case of metastatic angiosarcoma of the gingiva originating from a primary mediastinal lesion. The patient was an 83-year-old man who presented with a maxillary interincisor tumor; it was a painless mass with rounded superficial necrosis measuring 23 mm× 17 mm on the labial side and 20 mm× 17 mm on the palatal side. The histopathological diagnosis was of an epithelioid angiosarcoma. Imaging revealed lesions in the mediastinum, lungs, liver, and skin. The primary lesion was considered a mediastinal lesion. As the tumor had spread throughout the body, palliative therapy was administered. However, the patient's general condition deteriorated rapidly, and he died 3 weeks after the first visit. Identifying oral metastatic malignancies may result in detection of malignant tumors at other sites; thus, oral and maxillofacial surgeons must maintain a heightened awareness of angiosarcoma.