This study investigates ethical dilemmas of teacher-librarians in their professional practice. Within the framework of “Librarians’ Statement of Ethics” by Korean Library Association, the study used the survey and semi-structured interview with teacher-librarians. 259 teacher-librarians responded the survey and 5 teacher-librarians participated the interview. The survey was analyzed using descriptive statistics to find how often teacher-librarians experience ethical dilemmas. The semi-structured interview was transcribed and analyzed to draw the individual cases of teacher-librarians’ ethical dilemmas. The results indicate that teacher-librarians experience ethical dilemmas in relation to information access and intellectual freedom most often. It was difficult for teacher-librarians to relate their professional duties with their expertise and that they were not clear on how to avoid copyright issues and how to deal with the balance between users and copyright holders. This study had implications that individual dilemma cases are so context-dependent that teacher-librarians had to make decisions individually. They tried hard to find the balance between protecting students from harmful resources and library ethics. Researchers and practitioners need focus more on finding where the balance is and how teacher-librarians deal with their ethical dilemmas.