The new public management (NPM) has spread around the world. Agencification, which is a separation of government into policy and execution functions, is not exceptional. While the process of organisation change differs among countries and services, many studies for innovation in the public sector have considered the transition collectively, i. e. a change from traditional administration to public management. This paper develops a new interactive staging model for organisational transition. The model divides the public services into four types in terms of
interdependency and measurement objectivity of the composed activities, and also it considers interactions between internal and external actors of the organisation in the initiation, design and implementation stages. The new model is applied to agencification of the national museums in Japan, which is the transformation of cultural organisations providing a service composed of multiple activities.