The purpose of this study is to determine whether the pre-evaluation of the feasibility of establishing a public library, which is mandatory according to the revision of the Library Act, can improve the quality of the library. Therefore, the effectiveness of the preliminary evaluation was analyzed through the case analysis of the preliminary evaluation of the public library construction support project, which was implemented for the same purpose before the revision of the Library Act. In the case of libraries built after preliminary evaluation, most of the minimum standards for legal librarians required by the Enforcement Decree of the Library Act were secured, which helped secure basic library personnel. However, there were few libraries that secured and operated as much manpower as originally planned, and in some cases, the application applied to operate the library directly, but it was changed to consignment operation at the time of opening, so the pre-review details were not faithfully reflected. This study proposed re-establishing realistic librarian placement standards according to the revision of the law and introducing a post-evaluation using the library registration system so that it would not be a formal pre-process through case analysis.