The purpose of this study was to measure the professional identity level of public librarians and to identify related factors. For this purpose, a questionnaire survey was conducted for librarians in public libraries in Seoul and Gyeonggi Province from October 28 to November 18, 2021 and 375 valid responses collected were analyzed. As a result of the study, among the factors of professional identity public librarians showed high level of professional identity in order of belief in self-regulation, sense of calling to the field, belief in public service, using the professional organization as a major referent, and autonomy. In addition, librarian’s age, career, position and whether the director of the library was a librarian had a statistically significant difference in professional identity. This study has a significance in that the Hall Professionalism Inventory was used to measure participants’ professional identity and it associates domestic public libraries’ settings with professional identity.