A method for performing a security procedure by a terminal in a wireless communication system, and an apparatus thereof. The method includes transmitting a first access request message for accessing a first network of a core network to a first radio access network (RAN) node, performing an authentication procedure for mutual authentication with a node performing an authentication server function (AUSF) of the core network, generating a common key commonly used in one or more networks included in the core network based on an authentication vector obtained through the mutual authentication procedure, generating a first base key of the first network based on the common key and a network code corresponding to a type of the first network, and receiving an access accept message indicating an access accept of the first network from the first RAN node.