In this paper, we propose a user's position and behavior estimation method using sensors, such as a GPS device, an acceleration sensor, and an ultrasonic sensor, to alert important information to the user at just the right time. For exam pIe, the information obtained by the acceleration sensor can be used to estimate the user's behaviors and the position on the rail track where the train is, and the data measured by the ultrasonic sensor tells the distance to the ceiling, that is to say, the user's location, such as indoor/outdoor, on the platform, in the station premise, on the train, and in the campus building, can be detected. The evaluation result based on the field experiment proves the effectiveness of the proposed method with the accuracy of more than 90%.