In this article, we focus on a relationship between presidentialization and party politics. Especially, we pay attention to the governance of party politics. According to Thomas Poguntke and Paul Webb, phenomenon of presidentialization “denominates a process by which regimes are becoming more presidential in their actual practice without, in most cases, changing their formal structure, that is, their regime type.” They refer to as three faces of presidentialization, that is, (1) the executive face, (2) the party face, and (3) the electoral face. These faces are complementary in the democratic governance. In this paper, the phenomenon of presidentialization means the governance of party politics. There are two types of governance by political parties. One is “governance in the party” and another one is “governance among the parties.” It is useful for us to understand the changes of party politics by using the concepts of “governance in the party” and “governance among the parties.”