MANET composed of only moving nodes is concerned to core technology to construct ubiquitous computing environment. Also, it is a lack of security because of no middle infrastructure. So, it is necessary to intrusion detection system which can track malicious attack. In this study, cluster was used to stable intrusion detection, and rule about various attacks was defined to detect accurately attack that seems like network problem. Proposed method through experience was confirmed that stable detection rate was showed although number of nodes increase.