This study aims at identifying the influence factors on public library patron numbers through a time-series analysis using the Korean National Libraries Statistical Data from 2014 to 2019. The facts found can be summarized as follows; First, the variables of books collection and periodicals appeared constantly to be unsignificant in the influence on public library patron numbers through the period from 2014 to 2019. This suggests that the internet may be substituting public libraries in the service of access to ordinary books and periodicals, which has been considered as a main function of public libraries. Second, such factors as cultural or books programs, library operation, user activities, and facilities turned out to be more significant and continual in the influence on public library patron numbers than the factor of books collection and storage. This means that public libraries have a complementary relation with the internet in these fields.