Purpose: The study was to identify factors associated with post-traumatic growth (PTG) in patients with breast cancer based on Tedeschi and Calhoun’s model of PTG. Methods: The participants were 150 patients who were diagnosed with breast cancer at C University Hospital and were undergoing treatment or attending regular follow-up visits after the completion of all treatments. Data were collected using structured self-administered questionnaires from January 20, 2021, to February 24, 2021. The data were analyzed through linear multiple regression. Results: Factors associated with PTG were resilience (β=.51, p<.001), social support (β=.25, p<.001), and deliberate rumination (β=.14, p=.030), and these variables explained 45.0% of PTG. Conclusion: Resilience was included in this study instead of self-exposure in Tedeschi and Calhoun’s PTG model. Oncology nurses should actively intervene to increase personal resilience, to strengthen social support systems, and to encourage patients to perceive breast cancer occurrence as a meaningful event since breast cancer patients can experience PTG throughout the entire period of treatment and post-treatment. A revised model should be validated in future studies.