Security is something that is absolutely desirable by everyone. With a sense of security, people will not feel worried. For that we need a security information that is fast and effective so that security employees can immediately find out information if there is a theft in the room that is secured. This final project discusses about a room security system that is equipped with a PIR sensor that is installed at the entrance of a room or at a point considered important to be given a security system. Passive infrared sensor will be installed on the door of the room, then as an processor the Arduino microcontroller is used. Then to inform using LEDs as an indicator, buzzer as a warning siren and LCD as a text notification of the state of the situation. This system works, the PIR sensor will detect the presence of people or not in a room that is given this security system, then the Arduino microcontroller will process the data to order that the alarm sounds and give notification on the LCD that there is movement in the room. Passive infrared Receiver used is the KC778 R PIR sensor then the PIR sensor range used in the system has a maximum range of 60.