Room monitoring is an important thing in security. By using CCTV camera technology, room monitoring can be easier done. But, CCTV camera needs huge storage because the camera always record everytime, in the other side the result of recording just only can be seen directly on the storage. To handle the disadvantage, so it was built a room monitoring system that use webcam to replace CCTV camera, this system use a motion detector. This system also given a function that makes it is possible to access the result of room monitoring from the mobile device. This system use PIR (Passive Infrared) sensor that can detect human’s body temperature to do motion detector function. This software use C# programming language for desktop software, Java ME for mobile software, PHP for web software, and MySQL for its database server. The result of design and analysis in this final assignment is a software that can do room monitoring function that equipped with a motion detector and a software that can access the result of room monitoring from the mobile device.