Purpose: This study aimed to investigate whether cognitive behavior therapy (CBT) was effective as a standard intervention for temporomandibular disorders (TMD). Materials and Methods: The subjects were 134 TMD outpatients with no history of treatment for TMD. They had pain persisting for 1 month or more and/or limited jaw movement. All patients underwent CBT. Symptom fluctuation was evaluated by a self-administered questionnaire. Results: Symptoms had disappeared and improved in 112 patients within 2 months. Conclusion: It was suggested that most TMD symptoms can be relieved only by CBT in less than 2 months without further intervention.