This study tries to reveal the characteristics of the authorized textbook development system in Korea through the experiences of the teachers participating in the writing of the textbook and in its selection. For the data, the relevant teachers were interviewed and the contents were qualitatively analyzed. Textbook writers are burdened by the worries about content-related disputes, passing of authorization process, having many textbook selections, and following the consensus of the co-authors. And the textbooks are diversified by the complementary materials and unique formats. Since the sameness mechanism exerts more, teachers face similar textbooks among which they have to choose. Seeing this situation, teachers misunderstand the policy of expanding the authorized textbooks, select textbooks paying attention to external factors such as design, monopolizing textbook, and publisher websites. This revealed Korea’s authorized textbook development system formed by a conservative interpretation of the authorization criteria, the government’s inertia to regulate what is taught in the classroom, and teachers who prefer textbooks approving rapid preparation of lessons. In order to realize the original goal of the policy, diversification of textbook development needs to be ensured first.