Purpose: This study was done to develop tool to evaluate the core competencies regarding nursing cancer patients on chemotherapy, and to verify the reliability and efficacy of the developed tool. Methods: A tool to evaluate the core competencies was developed from a preliminary tool consisting of 112 items verified by expert groups. The adequacy of the preliminary tool was analyzed and refined to the final evaluation tool containing 76 items in 8 core competencies and 18 specific competencies. The evaluation tool is in the form of a self-report, and each item is evaluated according to a 3-point scale. From September 22 to October 14, 2011, 349 survey responses were analyzed using SPSS 20.0 and the WINSTEPS program that employs the Rasch model. Results: Results indicated that there were no inappropriate items and the items had low levels of difficulty in comparison with the knowledge levels of the study participants. The results of factor analysis yielded 18 factors, and the reliability of the tools was very high with Cronbach's α=.97. Conclusion: The results of this study can be used for training and evaluation of core competencies for nursing cancer patients, and for standardizing nursing practices associated with chemotherapy.