The purpose of this study is to propose ways to find the most optimal location of a social service facility to be built in a certain region. To that end, this study proposed the physical index, through which the degree of utilization - the extent to which a social service facility is used by the public - of a social service facility is measured. Second, as the degree of utilization obtained from the first phase and the degree of convenience indicating facility user satisfaction do not have proportional linear relationships, this study suggested an equation that can effectively represent such relationships through the queueing theory and the analytical hierarchy process (AHP) technique. Third, in this study, we proposed ways to calculate the total increase in the degree of convenience - degree of easiness to use a social service facility - by using the equation obtained from the second phase, and the methodology to select the location that has the largest increase in the degree of convenience as the optimal location. Even though this study was limited to the library, one of the social service facilities, the methodology employed by this study is expected to be effectively and significantly applied to other types of social service facilities.