Angiosarcoma is a highly malignant neoplasm, which most often develops on the scalp or face of elderly people. Common distant metastatic sites include the lung, liver, lymph nodes, and skin. We report a case of angiosarcoma manifesting as simultaneous bilateral spontaneous pneumothorax secondary to pulmonary metastases in an 86-year-old man. The pneumothorax preceded the diagnosis of angiosarcoma. Chest computed tomography showed multiple thin-walled cavitary metastatic pulmonary lesions, which increased in size as new lesions appeared over the clinical course of several months. This case suggests that a finding of simultaneous bilateral spontaneous pneumothorax may indicate a serious parenchymal lung disorder.