Up until now, studies on ‘museun’ focused on functions of interrogatives and infinitives. However, this research looks into ways in which ‘museun’ is used as discourse marker in spoken language rather than interrogatives and infinitives. Discourse marker usually influences discourse structure or information structure, and it acts as a significant function of discourse which shows the speaker’s psychological attitude or relationship with the hearer. In this research, the object of study was conversations between characters that appear in Korean semi-spoken corpus. Here, ‘museun’ in various contexts will be analyzed to understand its functions as discourse marker, and this analysis will be compared with preceding researches to look at the differences. Therefore, the purpose of this research is to understand the actual function of ‘museun’, which cannot be defined as interrogatives and infinitives, in spoken discourse. (Yonsei University)