Abstract: Vehicular Ad hoc Networks (VANETs) are a foundation of the visualized Intelligent Transportation Systems (ITS). Vehicular ad hoc networks are an easy target to attacks as they run in an open medium and use collaborative strategies for network communications. To acquire a tolerable level of security for Vehicular Ad hoc Networks (VANETs), traditional security solutions like encryption are combined with intrusion detection mechanisms. Vehicular ad hoc network does not have central network authority where the Intrusion Detection System (IDS) can collect, log and analyze audit data for the whole network. One approach is to have an IDS client running on each and every individual VANET node which runs a local detection engine analyzing own log information to detect anomalies. A cooperative detection mechanism takes decision whether there is an intrusion with all the nodes participation in the decision process by voting. But VANET nodes typically have limited resources which is not efficient in making each node as a monitoring node which keeps a database to find out an intruder or to save information about intruder. Thus, in this study we propose the concept of a cluster by grouping of direct-link nodes which can randomly and impartially select a monitoring node, the Cluster Head (CH). The Cluster Head (CH) provides security by collecting information from other Cluster Members (CM) and make database and executing an intrusion detection algorithm on cluster head only instead of running IDS on every VANET Node (VN). This scheme provides a security and offers a new approach to save consumption of limited resources of vehicular ad hoc networks.