In this era of technology all the technical domains are continuously grown and develop. The evidence of this growth is different kinds of communication devices is common for all persons. As the domain of communication is grown need to provide high performance end to end reliable delivery is increases. At the same time security measures is a one of the most issue in communication system. In this project we are study different effects of Black hole attack on MANET over Ad-Hoc on Demand Distance Vector and Optimized Link State Routing protocols. Moreover it we provide the comparative study for which protocol is most of the time effecting with this attack. And finally we provide a common way to detect and prevent the black hole attack over both protocols