The patient was 70-year-old man. He had complained of general fatigue and hoarseness for 5 months. Chest computed tomography scan demonstrated a large anterior mediastinal tumor. The diagnosis of high grade malignant sarcoma was established with needle biopsy and the complete resection through median sternotomy was conducted. The tumor was histopathologically diagnosed pleomorphic liposarcoma. Six months after operation, right supraclavicular lymph node metastasis was noted. Radiotherapy was performed, but the liver metastasis appeared subsequently 16 months after operation. Pleomorphic type is considered one of the poorest prognostic liposarcoma and should be required special attention.