Japan has been a super-aged society in the recent years; thus, there is a need for mobility support for elderly people with difficulty in moving and walking. We aim to provide a mobility support using a mobile robot considering movement from a facility to home through indoor and outdoor environments. A seamless positioning system is necessary for realizing such a community. This study proposes a seamless positioning system that can obtain position data of both indoor and outdoor environments. We develop a system combining ultrasonic beacons and a global positioning system receiver to obtain the seamless location position. We install the proposed system and verify the positioning system by a basic experiment.