Purpose: The purpose of this study was to identify aging anxiety and influencing factors of middle-aged adults. Methods: Descriptive correlation design was used. Three hundred and three middle-aged adults participated in the study and completed the questionnaires in the period from September 11 to October 15 of 2011. The data was analyzed using independent t-test, one-way ANOVA, Scheff$acute{e}$ test, Pearson correlation coefficients, and hierarchial multiple regression analysis. Results: Aging anxiety of middle-aged adults was higher than a moderate level. Socio-demographic variables such as age, religion, education, economic level, perceived health status and experience of living with older adults influenced significantly on aging anxiety. In contrast, general self-efficacy, aging knowledge and attitude toward older adults were negatively correlated with aging anxiety. Hierarchial multiple regression analysis incorporating these variables showed an explanation rate of aging anxiety at 21%. And religion, perceived health status, attitude toward older adults, and general self-efficacy were statistically significant among variables that influence on aging anxiety. Conclusion: The findings of this study suggest that senior preparation programs that can enhance self-efficacy, induce positive attitude on older adults and promote health should be implemented to reduce aging anxiety of middle-aged adults.