At present, people commonly used Gas LPG widely in households. Gas LPG is the major fuel in cooking. Sometime have a problem about the gas leak, it will cause danger. The security system has come to play an important role in accident prevention, which may occur unexpectedly, both life and property to reduce the risk that caused the loss. From the problems of gas leakage, this led to the fire. Cause the concept in creating a gas leak detector. By LPG gas detector that will leak as the cause of the fire. The gas detector saves device, electrical appliances, and properties of the residents. The gas detector can be alerted via cell phone immediately when a gas leaked. For the convenience and safety of the users even more. So that users know and solve problems as they arise. This gas detector will divide the composition of work into 2 parts, are hardware part and software part. Hardware part has 2 types about the work of Gas Detector and Valve. Software part is about notification by using the sim com module. And bring all three devices connect together by coding Arduino Program In order to be equipped with accurate and secure.