Mantle cell lymphoma (MCL) is a subtype of B-cell non-Hodgkin's lymphoma. Most cases of MCL have extranodal involvement at the time of the initial diagnosis; however, endobronchial involvement is rare. An 87-year-old man was referred to our hospital because of dyspnea on exertion. A chest CT revealed diffuse irregular wall thickening of the trachea and bilateral bronchi. A bronchoscopy revealed a diffuse irregular surface of the tracheal and bilateral bronchial mucosa and polyposis-like lesions. He was diagnosed as having MCL based on an endobronchial biopsy, and the diagnosis was confirmed using immunohistochemical staining.