Purpose: The purpose of this study was to identify the influence of posttraumatic growth and meaning in life on health promotion behavior in cancer patients. Methods: The participants were 124 cancer patients who were treated at a general hospital in Pusan. Data were collected for posttraumatic growth, meaning in life, and health promotion behavior. The data were analyzed using descriptive statistics, t-tests, ANOVA, Pearson correlation coefficients and stepwise multiple regression with SPSS 21.0. Results: The mean scores were health promotion behavior $2.72{pm}0.47$, posttraumatic growth $3.38{pm}0.89$, and meaning in life $3.29{pm}0.59$. The scores of health promotion behavior were significantly different by gender, perceived economic status, and economic difficulties due to diagnosis. Health promotion behavior had a significant correlation with posttraumatic growth and meaning in life. In multiple regression analysis, meaning in life and posttraumatic growth accounted for 26.0% of health promotion behavior. Conclusion: Posttraumatic growth and meaning in life were important factors that could be used to improve the health promotion behavior of cancer patients.