Pazopanib, a multitargeting tyrosine kinase inhibitor, has single-agent activity in patients with advanced soft-tissue sarcoma. Herein, we describe 2 cases of pneumothorax that occurred during pazopanib treatment in patients with soft-tissue sarcoma. These 2 patients had multiple lung metastases. According to previous reports and our past experience, the risk of pneumothorax may be higher in patients with multiple lung metastases. Although a causal relationship is uncertain, the risk of pneumothorax when prescribing pazopanib for these patients should be considered.