A 24-year-old right-handed man suffered right olecranon and lateral epicondylar fracture from high energy trauma. Fixation of olecranon was performed by a previous doctor. Three months after operation, he presented with limited range of motion (ROM) of the right elbow caused by malunion of the lateral epicondylar fracture and subluxation of the radiohumeral joint. Preoperative ROM of the right elbow was flexion 110° and extension -75°. Forearm rotation was pronation 85° and supination 65°. Fragment excision of the lateral epicondyle, which was 27 mm in length, and lateral collateral ligament repair using anchors were performed. Fourteen months postoperatively, contracture release of the elbow was performed. Twenty-four months postoperatively, radiograph of the elbow showed normal congruence without osteoarthritic changes and the ROM of the right elbow was flexion 120° and extension -35°. Forearm rotation was pronation 90° and supination 70°. In the surgical setting, in case of the size of the lateral epicondylar fragment is relatively large, the fragment should be fixed or lateral collateral ligament should be repaired when the instability of the elbow is found.