In Japanese, bare noun phrases can refer to the object that is introduced in a previous context, whereas in English, the definite article is required for a common noun phrase to refer. The research question of this discussion is whether Japanese syntactically projects a determiner phrases (DP) although it does not have an article such as the in English. If Japanese does not project DP unlike English, the definiteness of referential arguments needs to be parameterized in syntax and in semantics. On the other hand, if Japanese projects DP, it suggests that DP is part of Universal Grammar (UG) and thus that no parameterization is called for. This thesis presents three pieces of evidence to support the DP hypothesis for Japanese by examining nominal collocation constructions such as watasitati 3-nin ‘we three’and watasitati sensei ‘we professors’.