Hydrologic responses in watershed are determined by complex interactions among climate, land use, soil and vegetation. In order to effectively investigate hydrologic response in watershed, one needs to analyze the characteristics of climate as well as other factors. In this study, the relative contribution of climate factors and watershed characteristics on hydrologic response is investigated by using hydrologic indexes such as the aridity index and the Horton index. From preliminary analysis, it is shown that the Horton index is proper in terms of classifying hydrologic responses in main natural watersheds of south Korea. While climate and watershed characteristics both contributes to hydrologic responses, the degree contributed from each factor is changed depending on annual climatic humid conditions. In dry conditions, the climate factor is the predominant influence on hydrologic responses. However, in wet conditions, the contribution of watershed characteristics on hydrologic responses is relatively increased.