Provided are a method of performing public land mobile network (PLMN) selection and a device supporting the method. According to one embodiment of the present invention, a method for performing PLMN selection in a wireless communication system includes: entering an RRC_INACTIVE state; transmitting, to a non-access stratum (NAS) layer of the UE, information on whether or not there is on-going data; receiving, from the NAS layer of the UE, a request of a PLMN searching when there is no on-going data; and performing the PLMN searching based on the request of the PLMN searching.