1. A method for performing a Non Access Stratum (NAS) procedure in a multi mode NAS (mNAS) module of a multi-mode terminal, the method comprising: receiving a NAS procedure request signal from a user, and selecting a first NAS; transmitting the NAS procedure request signal to a NAS module corresponding to the first NAS; receiving a NAS procedure response signal including an execution result of a first NAS procedure between the NAS module corresponding to the first NAS and a network, from the NAS module corresponding to the first NAS; performing synchronization between the NAS module corresponding to the first NAS and a NAS module corresponding to a second NAS according to the first NAS procedure execution result; transmitting a NAS procedure response signal including the first NAS procedure execution result to the user; receiving a NAS procedure failure response from the NAS module corresponding to the first NAS, when a handover occurs in the first NAS procedure; transmitting the NAS procedure request signal to the NAS module corresponding to the second NAS, when the handover occurs in the first NAS procedure; and receiving a NAS procedure response signal including an execution result of a second NAS procedure between the NAS module corresponding to the second NAS and the network, from the NAS module corresponding to the second NAS, when the handover occurs in the first NAS procedure.