Purpose: The purpose of this research was to provide basic data in the control of depression found in patients with fibromyalgia by analysing the main factors that affect them. Method: The subjects were 207 out-patients in three university medical centers diagnosed with fibromyalgia according to the conditions by American College of Rheumatology (1990). Depression was measured by the CES-D Scale. Dependant variables, such as stress and anxiety were measured by the VAS Scale and physical activity was measured using 10(4-point-scale) questions developed by the researcher. The number of tender points was converted to scores based on the criteria of the ACR(1990) and of Yunus. Self-efficacy was measured by the Self-Efficacy Scale developed by Lorig et al. (1989) for arthritis patients. Result: The main factors that affect depression of patients with fibromyalgia were self-efficacy, anxiety, physical activity, tender points fatigue, and family support, which explained 49% of the depression. Conclusion: It has been confirmed that the regression equation model of this research may serve as a predictor of depression in patients with fibromyalgia.