Intraosseous vascular malformation, a representative vascular disease, rarely occurs in the oral and maxillofacial region, especially the maxilla. An 18-year-old female patient was referred to our department with the chief complaint of a radio-opaque mass in the maxilla. A biopsy was attempted at a local dental hospital before visiting our hospital, but it was not completed due to severe intraoperative bleeding. The patient presented swelling and induration in the right maxillary region without pain, local heat, or fluctuation. According to radiographic and clinical examinations, intraosseous vascular malformation or a bone-forming tumor such as aggressive osteoblastoma was suspected. Therefore, an open biopsy of the lesion was performed under general anesthesia. Histopathological examination revealed that the lesion consisted of bony trabeculae with fibrous connective tissue and numerous vascular structures, and the lesion was diagnosed as intraosseous vascular malformation.