In this paper, studied was the application of IT and sensor technology to trains in order to provide safety and convenience for passengers. One of applications is Lavatory Emergency Detection System in a train. Since a lavatory in a train is securely separated space, it is hard to notice an emergency inside of it unless a user sends a request for help. A system that can detect an emergency by using sensors was presented. System requirements were analyzed to design and implement a system. Prototype of the system was made. Then, tests in a laboratory were carried out based on a set of test plan to verify the system functions. Performance was turned out to be very successful. The system developed may have a chance to be installed according to the requirements of specifications of the train to be ordered.