Purpose: The purpose of this study was to identify factors that influence on medication adherence to oral anticancer drugs. Methods: 147 cancer patients receiving oral anticancer drugs were surveyed. The survey content included medication adherence, social support, depression, self-efficacy and symptom experience. Results: The mean medication adherence was 6.77 based on 8 points (84.6 based on 100 points). The influencing factors on medication adherence were symptom experience (β=-.19), decision of oral chemotherapy (β=.25) and social support (β=.21), and 17.0% of the variance in medication adherence was explained by these three factors in stepwise multiple regression analysis. Conclusion: The level of medication adherence to oral anticancer drugs was relatively high, and increased by decreasing symptom experience, and increasing social support. Considering the medication adherence is related with positive treatment outcome, nursing effort to improve medication adherence by decreasing symptom experience, and increasing social support is needed.