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, that includes an execution result of a 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 NAS procedure execution result; and transmitting a NAS procedure response signal including the NAS procedure execution result to the user.