Purpose: The purpose of this study was to examine the effects of self-efficacy promotion programs on self-efficacy, self-care behavior, and quality of life in breast cancer patients receiving radiation therapy. Methods: This study was conducted from November 1, 2009 to December 10, 2010. A total of 39 breast cancer patients, who received radiotherapy in a University hospital located in city B, participated in the study and were divided into two groups (experimental group 17 and control group 22). The data were analyzed with the ${chi}^2$-test and ANCOVA using the SPSS/Win 17.0 program. Results: Self-efficacy promotion programs aimed at self-management were effective in enhancing concrete self-efficacy but not effective in promoting general self-efficacy, self-care behavior, and quality of life among breast cancer patients who have received radiotherapy. Conclusion: Organizing a support group for the breast cancer patients seems to be highly necessary to help themselves obtain higher level of specific self-efficacy, self-care behavior, and quality of life in general. It will also be beneficial for the breast cancer patients to understand their unique situations and improve their health problems for themselves.