Congenital cystic adenomatoid malformation [ C.C.A.M.] is rare, but often fatal congenital lung bud anomaly that causes acute respiratory distress in the newborn infants. In those who survive infancy and early childhood, its clinical manifestations are not unusual to detect. Recently we experienced an infant with C.C.A.M. Type II. The patient was a 7-month-old male, and had been suffering from coughing and fever since 3 months ago. The symptom were not improved with medical treatment and then, exploratory thoracotomy was performed under the impression of infected C.C.A.M. or other congenital cystic disease.The left lower lobectomy was performed, and the postoperative course was uneventful.