Hemangiopericytoma is an unusual soft tissue tumor. A 54-year-old man presented with sudden onset of chest pain and dyspnea for 1 day. The initial chest x-ray showed a massive left pleural effusion. A contrast-enhanced computed tomographic scan of the chest showed a homogenously enhanced mass in the intrathoracic extrapulmonary space. A tube thoracostomy was performed and hemothorax was confirmed. A posterolateral thoracotomy was performed and a tumor in the parietal pleura of the left chest wall was resected. Grossly, the resected tumor arose from the parietal pleura, and the cut surface was elastic, soft, and pale yellow. There were several cystic formations and hemorrhages. Based on histologic findings, hemangiopericytoma with lower grade malignancy was diagnosed. The patient was alive and free from tumor recurrence 1 year after surgery. Intrathoracic extrapulmonary hemangiopericytoma is extremely rare, and surgical excision is the treatment of choice. Adjuvant chemotherapy or radiotherapy is indicated because of the high risk of recurrence and potential malignancy.