Diaphragmatic eventration is a rare anomaly. When patients with this condition undergo general anesthesia, anesthetic management should be performed with particular care owing to the risk of diaphragmatic rupture. Such a rupture can be perioperatively diagnosed using multiple tools including lung ultrasonography. This case report describes the anesthetic management of a male infant with osteochondroma in the distal ulna, presenting with diaphragmatic eventration on the right side.