This paper examines the relationship between a democratization of party leadership selection and party organizational change in Japan. The Liberal Democratic Party, the long ruling party, became used to utilizing votes by party members as a method of electing its presidents. Compared with the Democratic Party of Japan, the second largest party, LDP has a much larger number of members, but its factional linkage which holds diet members and rank and file party members together has dwindled. By contrast, the organizational support base of DPJ remains weak, so the demand of local party organizations for votes by party members does not increase. In sum, as a result of many LDP members voting individually, they are coming on the stage of party leadership selection as new actors. Both because the incentives of candidates and members change, votes by party members became popular in LDP.