Promoting the use of public transport (PT) is considered to be an effective way to reduce the number of passenger cars. The concept of Mobility-as-a-Service (MaaS), which began in Europe and is now spreading rapidly around the world, is expected to help to improve the convenience of PT on the viewpoint of users, using the latest information communication technology and Internet of Things technologies. This paper outlines the concept of MaaS in Europe and the efforts made at the policy level. It also focuses on the development of MaaS from the viewpoint of promoting the use of PT in Japan.