Graeseo’ is a conjunctive adverb that is commonly used for both spoken and written languages, but has hardly been studied as an independent topic. This study investigates the syntactic aspects and semantic functions of ‘Graeseo’ in spoken language, such as conversations and speeches. ‘Graeseo’ is differently used in spoken languages from written, such as its location, conjunction unit or by the conversation participant, and plays diverse semantic roles thereby. In spoken languages, just as in written, ‘Graeseo’ is used to connect two sentences when the preceding one indicates causes or reasons. This causational connection leads development of the conversation or speech. In other cases, ‘Graeseo’ is used to present supplementary, detailed or repeated explanations, sequential relations or simple connection in spoken languages. When a speaker uses ‘Graeseo’ in the context where there is no causational relations, it could be seen that s/he desires to emphasize that her/his speech is cohesive and coherent. That is, ‘Graeseo’ is a useful means to connect one``s speech by causational relations and help maintaining the right to speak.