This paper aims to give a diachronic and synchronic account of the development of interrogatives as discourse markers in Korean. Drawing on C-H. Kim (2000), this paper posits four hypotheses about the historical development of interrogatives: (a) interrogatives-only hypothesis, (b) interrogatives-first hypothesis, (c) indefinites-first hypothesis, and finally (d) indeterminates-first hypothesis. Based on the historical evidence from C-H. Kim (2000), it is shown that interrogatives started to have divergent meanings in the late 18th century, and that there was an intermediate stage where the interrogatives were first used in indirect questions before they began to be used as indefinites. It is shown, furthermore, that the development as discourse markers follows very shortly historically. Of the interrogatives used as discourse markers, this paper examines mwe 'what' and way 'why', and claim that mwe is a speaker-oriented subjective marker whereas way is a hearer-oriented intersubjective marker.