Purpose: This study was attempted to verify the effects of Tai Chi exercise on the depression and self efficacy of the patients with rheumatoid arthritis. Method: It employed a non-equivalent control group pre- and post-test design. The research instruments used in this study were depression and self efficacy. Thirty-two patients in the experimental group carried out 50 minutes of Tai Chi exercise for 12 weeks, and 29 patients in the control group did not. Before and after the experiment, both groups were tested for depression and self efficacy. Collected data were processed using the SPSS/WIN 10.0 program analyzing by the frequency, percentage, $X^2$- test, and t-test. Results: Depression significantly decreased in the experimental group. However the improvement in self efficacy of the rheumatoid arthritis patients was not statistically significant but slight enhancement was. Conclusion: Tai Chi exercise is an effective nursing intervention that can be used for rheumatoid arthritis patients.