The Bulletin of the Institute of Human Sciences, Toyo University, No. 7 The Semantic Role and Function of GA and WO as object markers in Japanese WANG Yaxin The purpose of this paper is to analyze the semantic role and function of GA ( ) and WO ( ) in Japanese sentences. As markers to express object, ga and wo play different semantic roles. Wo marks an event with an agent and receives an active effect from the agent. By contrast, ga marks an event independently, and rejects any effect from the agent. Prototypical features influence usage of WA and GA, and shift the nuances of each sentences. Japanese semantics, object, agent, direct effect, indirect effect An associate professor in the Faculty of Sociology, and member of the Institute of Human Sciences at Toyo University