Purpose: The purpose of this study is to investigate the factors influencing oncology unit nurses’ pain management of cancer patients. Methods: This study was a designed descriptive correlation study. The participants of this study were nurses working in an oncology unit at a university hospital. A total of 135 nurses participated and data were collected between October 10 and October 31, 2018. Measures used for this study assessed nurses’ knowledge of cancer pain management, compassion competence, and the performance of cancer pain management. The data were analyzed using independent t-test, ANOVA, Pearson’s correlation coefficient, and multiple linear regression analysis. Results: Performance of cancer pain management was significantly correlated with compassion competence (r=0.37, p<.001) and difference according to the experience of cancer by the participants or family members (t=2.22, p=.028). Performance of cancer pain management was influenced by compassion competence (β=.36,p<.001) and the experience of cancer by the participants or family members (β=.17, p=.041). The explanatory power of this model was 14.4%. Conclusion These results suggest the need for cancer pain management education based on compassion empowerment. The findings shows that continuous cancer pain management education is required in consideration of the oncology nurses’ career and work characteristics.