Due to the rapid population's aging, the life span's expansion and social & cultural characteristics, the standards of age classes in senescence are changed. Thus, this study aimed to identify the influential factors on health care utilization in the elderly by age class, and targeted 2,937 adults in their ages over 55 years old from the Korea Health Panel's 2009 Yearly Integrated Data. This study investigated the target health care utilization in the elderly in relation with the gender, the education level, the health-care insurance type, the income, the current job state, the chronic disease. In order to analyze the influential factors on health care utilization in the elderly, the multiple linear regression analysis was conducted to the data. As the results from this study, Concerning the influential factors on the health care utilization, the income, the subjective health state, the chronic disease and the regularly meals for the young-old influenced. Concerning the influential factors on the health care utilization, the subjective health state for the old. Concerning the influential factors on the health care utilization, the subjective health state, the income for the older-old influenced. Concerning the influential factors on the health care utilization, the education level, the spouse, the economic activity and the drinking oldest-old influenced. Therefore, it will need to provide systemic health-care & medical services, to develop health-care & medical programs and the health-care & medical policies and to execute them according to the age classes in senescence.