Bochdalek diaphragmatic hernia is generally congenital and rarely diagnosed incidentally in adults. A 21-year-old man presented with a diaphragmatic hernia suspected during routine examination. Chest radiography showed the colon and small intestine herniating into the left hemithorax and the ileocecal appendix in the superior thoracic apertura. We performed a thoracoabdominal incision and the stomach, omentum, colon, and small intestine were retracted back into the abdomen. The diaphragm was repaired with Prolene mesh following adhesiolysis. Two months later, there was no recurrence but no lung expansion. The space was filled with effusion, but the patient had no complaints.