This research empirically analyzes the effect of internal marketing in public libraries on the quality of work life of public library librarians. To this end, a 59-day survey of incumbent librarians working at public libraries in Seoul was conducted on Naver Form from July 25, 2020, and 120 respondents were conducted using IBM SPSS 25, a statistical program, to conduct factor analysis, reliability analysis, frequency analysis, correlation analysis, and multiple regression analysis. Research has shown that internal marketing of public libraries has a positive effect on the quality of librarians’ work life. As a way to improve internal marketing in public libraries, it was suggested to prepare a systematic and sustainable internal marketing system, recognize experiences and compensate highly educated librarians, improve the compensation system of librarians, and promote an internal marketing system centered on supporting management and delegation.