This paper proposes a simple sensor systems development method for supporting elderly people,and the constructive method of a community using it,and verifies these significance and reactions of people involved in this pilot program.We have developed the sensor system with excellent cost performance by using a magnetic sensor and the Internet E-mail for the elderly single population.This sensor unit is able to interact with weak radio.If the behavior of the elderly is not detected a long time,each sensor unit which is installed at the entrance of each room flashes LED of all sensor units to communicate with each other.These illuminations disseminate noticeable information of the abnormal state of the elderly to neighbors and passers.At the same time,this system wll notify by e-mail in real-time to support staff and officials.Major role of this system behave as a trigger to widely contact a network of community members.