We encountered a case of entrapment of the ulnar nerve and artery associated with displaced distal radius and ulna fracture. After the closed reduction, a patient noted a severe sensory deficit and had claw hand. Intraoperatively, the proximal edge of the fractured radius was positioned in the space between the ulnar artery and the nerve, and the nerve was entrapped. The entrapment was released surgically with a good 1-year outcome. In cases of distal radius fracture, there is a possibility of entrapment of the ulnar nerve. When neurological symptoms worsen after the reduction maneuver, early nerve exploration is needed.