A 39-year-old man was admitted to our hospital for further evaluation of a consolidated shadow and clarification of the cause of serum tumor marker elevation (CA19-9 496.2 U/ml, CA125 160.6 U/ml). Chest computed tomography revealed a well-defined homogeneous nodule in the left S(10). Angiography showed one aberrant artery, branching from the ascending aorta. Intralobar pulmonary sequestration was diagnosed and the sequestrated lung was resected. Microscopic findings of the sequestrated lung showed a mucus-containing cystically dilated bronchus, which was covered with ciliated cylindrical epithelium. Immunohistochemical staining showed positive staining for CA19-9 and CA125 in both the ciliated cylindrical epithelium and mucus. Serum values of tumor markers returned to their normal range after surgery.