The concept of PCA(Patient Controlled Analgesia) was first described in 1968, by Sechzer. The earliest descriptions of actual self-administered PCA machines were by Forrest et al. In gastric bypass surgery, cesarian section, orthopedic surgery etc, PCA is widely used in the control of postoperative pain. Previous Studies have shown that PCA provides effective pain-control for the postoperative patient. The postoperative pain-control is a problem that should be solved in surgery. Especially in orthognathic surgery, it is not same as in the case of maxillofacial trauma surgery or of tumor surgery: most orthognathic surgery patients are under operation not accustomed to pains, and difficulties in pain-complaint due to IMF(Intermaxillary fixation), postoperative nausea, and vomiting are additional problem. In this study, we have compared PCA and IM analgesics with respect not only to time request but also to the quality of postoperative pain control.