Declining birthrate and aging population are common problems of developed countries. These cause increasing of single life of the elderly, and finally, increase the risk of lonely death of them. One of the best precautions against lonely death is the safety confirmation by a third person. So, the service of that for the elderly is spreading in various forms now. However, the service is not popular because of some kinds of problems, for example, workload, technical difficulty, and privacy. Therefore, the method using ambient sensors in the home has been proposed. In this method, some kinds of sensors are installed in living environment, such as motion sensor and door sensor and so on. These sensors have no personal information. The data is collected by sensors periodically and observed for safety confirmation. However, the sensor data have different meanings by lifestyle of residents. So, to determine the standard of safety, we have to consider the difference of lifestyle according to some conditions such as person and season. Hence, we aim to develop a new safety confirmation system which can optimize safety standard according to the resident's lifestyle. In this paper, we collected the sensor data of 19 elderly people for about 10 months and analyzed it as a first step of developing. As a result, we found the difference of sensor data in lifestyles according to residents and seasons.
