Objectives : The purpose of the study is to improve autonomous decision-making ability by analyzing the relationship between autonomy and decision-making ability. Methods : The subjects were 176 dental hygienists in Busan. Self-reported questionnaire was fill out from May 2012 to January 2013. Results : The average of the degree of autonomy was $2.20{pm}0.29$. Buddhists showed the highest score of $2.37{pm}0.37$ (p<0.05). Buddhists had the higher education than other religions (p<.05). Clinical decision-making ability was $2.21{pm}0.25$. Among the subcategories, statistically significant differences (p<.05) was shown by gender, degree of education, and religion in the domain of "Exploration of Choice and Alternatives"; Buddhists showed a higher score in the domains of "Assessment and Re-evaluation of Decisions" and "Review of Values and Goals," with significant difference of p<.05. Autonomy and clinical decision making revealed a positive correlation in the categories "Assessment and Re-evaluation of Decisions" (r=.518, p=.000), "Review of Values and Goals" (r=.610, p=.000), and "Investigation of Information and Synchronization of New Information" (r=.314, p=.000). Conclusions : To improve the performance of dental hygienists, working systems and training will be intensified to develop the autonomy and clinical decision making.