We have tried to show which different roles political parties in Europe and Japan played in forming the modern political economy regime in 1955-65. Especially we examined the relationship between political parties and states or interest groups in that forming process. Case studies adopted in our project are Japan in 1950's and 1960's, French Fifth Republic and West Germany.Nakakita's report shows how the Japanese 1955-regime as modern political economy regime was formed. He poses an interpretation that the political intention of 1955-regime building was to make a strong political power to carry out the demilitarization and the independence from USA.The economic one, according to his interpretation, was to get an economic power needed to adapt to the open international economic system under the USA initiative.In Sorai's report, "changes in 1960" is regarded as the most important political event in postwar Japan as well as the formation of 1955-regime. In 1960, the governing LDP changed the style of governance. In the same year, Socialist Party of Japan in opposition also changed her strategy to come to power. Japanese politics after 1960 was strongly determined by these double changes.Nakayama's theme is French political economy regime in the forming period of Fifth Republic. He makes it clear why and how moderate modernization policy, which party governments in Fourth Republic had been leading, was abandoned and radical modernization policy replaced it under the strong president's initiative.Iida shows how the problem "integration of group interests" was solved in West Germany in 1955-65. During this term, old-fashioned ideas of integrating interest groups (=plans of Federal Economic Council or Erhard's concept of "Formierte Gesellschaft") were vanishing. In place of state institutions, which were leading actors in traditional ideas, political parties began to play important roles to integrate group interests.