Sewerage supply system in Japan are facing various problems and issues in these days, such as decrease of tariff income according to population decrease and upgrading of large numbers of deteriorating facilities. Private-public partnership for sewerage management has been considered as one of the solutions to these issues. According to Ministry of Land, Infrastructure, Transport, and Tourism, the method of private-public partnership had been applied for 568 sewerage treatment plants and 29 pipeline infrastructures by March 2018. Among them, concession method, the most advanced method of private-public partnership, is applied to Hamamatsu city. Although effective sewerage management is expected, some issues are already recognized in application of concession method: For example, there are only few rooms for originality and ingenuity of private companies since increase of users and control of service level are quite limited in sewerage management. This paper aims to provide issues and solutions of smooth application of concession method to sewerage management using case analysis of actual projects in Japan.