The purpose of this study is to identify the underlying conditions that account for Japanese Prime Ministers controversial visits to the controversial Yasukuni Shrine, employing Institutional approaches. This study will show how Institutional approaches explain Koizumis continued visits. This study tries to contribute to theoretical arguments (Institutional approaches) as well as to empirical studies (Koizumis continued Yasukuni visits). Conventionally, this issue has been explained in terms of Prime Ministers individual beliefs and in terms of pressure on the Koizumi government from political interest groups. However, by focusing on ideas embedded in the Japanese institutionalized politics called the 1955 political system, this study will shed light on the underlying structure of this issue. The declining power of the Japan Socialist Party (JSP) and changing power balance among factions in the Liberal Democratic Party (LDP) can be interpreted as the keys to his visits.