With the rapid expansion of computer usage and computer network the security of the computer system has became very important. Every day new kind of attacks are being faced by industries. Many methods have been proposed for the development of intrusion detection system using artificial intelligence technique. In this paper we will have a look at an algorithm based on neural networks that are suitable for Intrusion Detection Systems (IDS). The name of this algorithm is "Self Organizing Maps" (SOM). So far, many different methods have been used to build a detector that Wide variety of different ways in the covers. Among the methods used to detect attacks in intrusion detection is done, In this paper we investigate the Self-Organizing Map method.