This study aims to examine interactive authenticity of speaking tasks presented in intermediate Korean textbooks, and to suggest ways to enhance the interactive authenticity. As the core principles of the Korean education, communicative language teaching, task-based language teaching, and learner-centered language teaching are emphasized, and it results that material developers have made great effort to include the authentic materials which reflect the real-world situations. However in order to increase the ability of task performance, the experience of classroom task performance should transfer to a real-world situation, thus more attention should be paid to the authentic process of task performance as well as authentic task itself. Therefore, in this study it is termed ‘interactive authenticity’ to refer this authentic process of task performance, and it is specified as follow: i) topic development, ii) turn-taking, iii) response utterance, iv) attitude and gesture. Among these, interactive authenticity of intermediate Korean materials is analyzed based on the framework of topic introduction, topic transition, and topic deepening. As a result, all materials analyzed in this study have devices to teach topic development. Especially expressions and devices to present the way to deepen given topic abound, but topic introduction, which helps to start discourse, and topic transfer, which extend discourse moving to other topic within given theme, are shown relatively small percentage. This study also gives actual example of topic development presented in analyzed intermediate Korean materials. Based on this, more effective ways to lead students to develop a seamless interaction. This study highlights on the need of paying more attention to the interactive authenticity when developing speaking tasks and teaching speaking tasks.