Benign tumor of the lung are relatively uncommon and leiomyoma among these is one of the rarest tumors. Because of salient features as well as the location of the leiomyoma, which led to the destruction of the lung and subsequent pneumonectomy, the importance of early diagnosis should be emphasized. Recently, authors experienced a leiomyoma of left main stem bronchus with complete atelectasis of the lung, resected with left thoracotomy and transverse bronchotomy in a 58 year old male. The tumor resected was composed of dense interlacing spindle cells by hematoxilin-eosin and also trichrome stains. At repeated bronchoscopic examination postoperatively, one and three months later, there was no evidence of any residual or recurrent tumors. For the universal rarity of the leiomyoma in the bronchus or lung and also there is no report in the reviews of the Journal of Korean Thoracic and Cardiovascular Surgery since volume one, 1968, authors report a case with the foreign literature reviews.