Everyone fantasies a home where all the appliances and devices work automatically. This is a small step towards achieving the features of the complete automation system for our home. There is a feature of automatic ON and OFF functioning of light that also depend upon if the person is available in the room. Remote controlled AC fan using an automatic disabling system. Fan speed will be changed according to our requirement. Security is the main concern for everyone. Everyone wants to live securely in his/her house to keep safe or secure from various incidents like theft. Nowadays, many times we hear news about a house robbery or theft in some houses, bungalows, flats. We all know that duplicate key can be created within a few minutes and also key duplication is easy. These are the disadvantages of the traditional locking system which uses a key and a lock. To overcome the above stated disadvantages of existing system we have designed a GSM based home security system. It can avoid these undesirable situations, and theft. PIR sensors are used to detect living object movement. PIR is a passive infrared sensor, which detect passive infrared rays.