A rare case of invasive thymoma with endobronchial polypoid growth is presented. A 68-year-old woman presented with coughing and sputum. The chest X-ray and computed tomography (CT) findings demonstrated a large mass with a calcified lesion in the left hilar region. A bronchoscopic examination showed a polypoid tumor in the left B3b bronchus. The tumor was surgically resected and revealed a unique polypoid endobronchial extension. This tumor was pathologically diagnosed to be invasive thymoma.