This study was designed to evaluate the pain control effect by morphine injection to masticatory muscle pain patients. Patients with masticatory muscle pain visited the Department of Oral Medicine, Kyung Hee University Dental Hospital were recruited to this study and diagnosed by RDC/TMD. Experimental group were divided into three group; saline injection group(n=10), lidocaine injection group(n=10) and morphine injection group(n=10). Evaluation list was the subjective pain evaluation(visual analogue scale, Mc Gill pain questionnaire, pain drawing) and the objective pain evaluation(pressure pain threshold, pressure pain tolerance) and evaluation time was injection before, after 10min, 30min, 60min and then it was analyzed statistically.The results were as follows : 1. The subjective pain evaluation and the objective pain evaluation were significantly different statistically in within subject effects(p<0.001). 2. The subjective pain drawing evaluation(p<0.001) were significantly different statistically in between subject effects. 3. The objective pressure pain threshold evaluation(p=0.025) were significantly different statistically in between subject effects. 4. The morphine injection group(p=0.001) were more significantly different than the saline injection group statistically in the subject pain drawing evaluation. Therefore, it was considered that the morphine injection was effective to pain control for masticatory muscle pain patients within 60 minute.