This paper looks at the transitivity alternation phenomenon in Japanese, evinced by the verbs suru ‘do’ and naru ‘become, ’ and tries to bring empirical evidence to support the proposal that these verbs are the counterparts of the two kinds of light verbs, v and v *, proposed by Chomsky (2001). An empirical basis is given for the existence of v/v *, and the result of the analysis clarifies the similarities and differences between the clause architecture of English and Japanese. From a theoretical standpoint, the result supports the Agree mechanism proposed by Chomsky (2001).