Populism is one of the most critical issues in Japanese urban politics. This case study examines urban populism through an urban regime analysis of the urban politics of Nagoya city, which has experienced populist politics since Mayor Kawamura took office in 2009. The most crucial point of this case study is the disintegration of the urban regime of Nagoya in the late 1990s. During the 1980s, this regime restructured itself with developmental and distributive politics. Business leaders supported developmental policies such as the conducting of mega events and building of public facilities. City politicians practiced machine politics and influenced the mayors. Such an urban regime lasted from the early 1980s to mid-1990s. However, the regime disintegrated in the late 1990s due to the weakening of machine politics. Politicians lost their power to mobilize voters, making voter behavior unpredictable. This created a power vacuum and made it easy for political leaders to get popular support through populist mobilization. In 2009, Mayor Kawamura was elected with over 500,000 votes (58.57％), and since then, Nagoya has experienced a political confrontation between the mayor and city politicians. This disintegration of the urban regime produced urban populism in the city. Populism is often considered to be a driver of political changes. However, in this case study, a rearrangement of the city regime brought about urban populism. This study indicates a potential for studies comparing the urban politics of Japan through urban regime analyses.