GSM BASED WIRELESS SECURITY SYSTEM USING PIR SENSOR ABSTRACT Human detection is a essential concept in the industrial sectors. Especially some hazardous sectors like boilers, reactors where only authorized person can enter. The entrance of unauthorized person at those sectors can cause some mishandling of the system leads to great accidents. Hence an efficient human motion detection system is needed. In this project we are using GSM based wireless system for the efficient communication and to avoid the unauthorized person involvement in the hazardous areas. The PIR sensor is used to detect the motion in any kind and will inform to micro controller. If the micro controller unit receives the detected signal, it will send a message through GSM modem.