This descriptive research is to provide preliminary data for the development of a nursing service program that ensures the safety of hemodialysis patients by identifying the effects of nurses’ critical thinking disposition and clinical decision making ability on the patient safety competence. The research participants were recruited through convenience sampling. The survey was conducted on 202 nurses who had worked for three months or longer in a hemodialysis unit. Critical thinking disposition was measured using the instrument to measure critical thinking disposition developed by Yun Jin (2004), and clinical decision making ability was measured using the Korean version of the Clinical Decision Making in Nursing Scale (Jenkins, 1985), which was translated and revised by Baek Mi-kyung (2005). The instrument to measure patient safety competence in this study is the one developed by Lee Nam-ju (2012) and then revised and supplemented by Jang Hae-na (2012) for clinical nurses. In summary, Consequently, education programs tailored for nurses according to their years of experience and position need to be developed and implemented. In addition, policies related to patient safety accidents should be prepared and continuous education should be provided for nurses working at a hemodialysis unit.