Abstract: In MANET (Mobile Ad hoc Networks) is highly vulnerable to attacks in this Routing attacks are most important because they will cause devastating damage to MANET. In order to deal with the routing attacks in the existing system we are using the binary or naive-fuzzy theory of cost sensitive intrusion response system in MANET. But this model cause unexpected network partition and additional damage, It took the subjective knowledge and objective evidence but omitted the logical reasoning part. So in proposed system we are using the risk aware response mechanism based on the quantitative risk estimation and tolerance.