A 64-year-old male was admitted due to weight loss of 5kg during a month. Chest X-ray showed two large, lobulated masses on both lower lobe. Chest CT showed ill-defined, multilobulated mass on left lower lobe and irregular, relatively homogenous mass with air-bronchogram on right lower lobe. Left lower lobectomy and right lower lobectomy was performed sequentially with three months interval. Microscopic findings showed squamous cell carcinoma of both mass. It was thought that this patient had synchronous double primary lung cancer.