A 69-year-old woman complaining of cough and wheezing of 2-months duration was admitted for diagnosis and treatment. She had been treated for bronchial asthma. Chest computed tomography showed an endobronchial tumor in the left main bronchus. Bronchoscopic biopsy yielded a diagnosis of plasmacytoma. We confirmed the absence of M-protein in the serum and urine, bone lesions in bone scintigraphy, and other organ dysfunction. In addition bone marrow biopsy and revealed normal findings. We diagnosed extramedullary plasmacytoma in the left main bronchus. We performed a sleeve resection of the left main bronchus including the tumor and reconstructed the bronchus with primary end-to-end anastomoses. We achieved complete excision and were able to maintain lung function. One year after the operation, the patient remains well, with no evidence of recurrence, or conversion to multiple myeloma. When a patient complains of wheezing, a bronchial tumor should always be considered.