A method, performed by a user equipment (UE), in a wireless communication system, includes: transmitting, to a network entity, a registration request message including network slice assistance information (NSSAI) corresponding to a slice; receiving a response message including rejection information on a registration for the slice in case that resource allocation has reached an upper limit; and determining to suspend a registration request for the slice, based on the response message, wherein the rejection information on the registration for the slice includes information on a back-off timer or information on a rejection cause.