This paper explores Korean demonstrative pronouns which change to discourse markers; ‘i’, ‘geu’ and ‘jeo’. In order to understand the cohesive change of meanings and functions of demonstrative pronouns, I introduced the approach of Grammaticalization which is defined as “an increase of the range of a morpheme advancing from less grammatical to a more grammatical status(Kurylowicz, 1965:52)” Demonstrative pronouns, ‘i’, ‘geu’ and ‘jeo’, are grammaticalized in direction of ‘demonstrative pronoun(noun-substitute) >demonstrative article> discourse marker([gap-filler(gaining time)])>[hesitation], or [gap-filler(gaining time)] > [self-repair elaboration])’. Here I suggest the change of Korean demonstrative nouns, ‘i’, ‘geu’ and ‘jeo’, as follows; (Hankuk University of Foreign Studies)