The mandibular contour determines the shape of the lower part of the face and thus influences the appearance of the face. A patient with a large, squarish, or broad face who desires a small, round, or slender face can undergo mandibular contouring surgery to reduce the width of the lower face. The successful correction of a prominent mandibular angle by conventional angle ostectomy has been reported. But, in the majority of patients with a widened facial appearance, both the mandibular angle and part of the mandibular body anterior to it are protuberant laterally, so both must be resected. The purpose of this study is to introduce a new method of performing mandibular contouring surgery, more effectively and easily, and to reduce postoperative complication and evaluate its results. We treated 6 patients who has prominent mandibular angle using multiple step osteotomy with angle-splitting ostectomy. The advantages of this new method are as following. (1) easily performable (2) effective mandibular contouring surgery by reducing the width of lower face (3) producing a natural relief of the mandibular angle (4) low risk of soft tissue damage and complications (5) shortening of the operation time. etc.