A 65-year-old male was admitted to our hospital for evaluation of an abnormal shadow in the left lung field of chest roentgenogram. A chest computed tomography scan revealed an ill-defined nodule in the superior lingular segment of left lung and a calcified nodule in the left pulmonary apex region. A diagnosis of lung adenocarcinoma in the left lingular was made by transbronchial cytology and the left upper lobectomy with lymph node dissection was performed. Pathological diagnosis was primary lung adenocarcinoma in the superior lingular segment of left lung (pT1aN0M0, stage I A) and hamartoma in the left pulmonary apex region. It was considered to be important to discriminate a hamartoma from a metastasic lesion in order to conduct correct treatment.