Hamartoma originated from the chest wall is rare. All reported cases are infant's ones. A 16-year-old man was admitted to our hospital because of chest pain and abnormal shadow in routine chest X-ray film. Thoracotomy was performed under the diagnosis of pulmonary sequestration in the left apical region. However, the operation revealed a tumor originated from the chest wall, which was diagnosed hamartoma by histological examination. Re-operation was required because of hemothorax caused by residual tumor. Second and third ribs were resected with residual tumor. There is no evidence of recurrence one year after the second operation.