MANET is a network with unrestricted mobility in nature and no centralised control. Mobile node can move from one network to another frequently. MANET is infrastructure less so any node can enter and exit the system at any time. Malicious node can enter easily in the network and degrade the performance of the network by modifying, updating and drop the data packet. MANET is vulnerable to various attack such as black hole, grey hole and coverage hole etc so the security is main issue in adhoc network. In this paper, many mechanisms have been proposed to detect the black hole in the network using an efficient adhoc on demand distance vector routing protocol (AODV) which improve the performance of the network by detecting black hole attack in MANET.