Objectives: This study is a descriptive research study to identify factors affecting the proficiency of core basic nursing skills of 3rd and 4th year nursing students. This study was conducted to use as evidence data for an intervention study to increase the proficiency of core basic nursing skills of nursing students. Methods: The subjects of this study were 184 people in the 3rd and 4th years of the nursing department at a university located in K city. They voluntarily agreed to participate in this study and filled a structured questionnaire provided. The questionnaire includes general characteristics, problem-solving ability, and proficiency in core basic nursing skills. The collected data were analyzed using descriptive statistics, t-test, one-way ANOVA, Schéffe test, Pearson's correlation coefficients, and multiple regression using the SPSS WIN 18.0 program. Results: It was found that the higher the grade, the higher the problem-solving ability, the higher the mastery of core basic nursing skills. Conclusion: In order to improve the proficiency of core basic nursing skills of nursing students, it is necessary to continuously provide opportunities for education and practice of core basic nursing skills and the application of educational content to continuously improve problem-solving skills from the lower grades.