A method of securing a Pseudonymous mobile subscriber ID, PMSI, of a Vehicle-to-Everything, V2X, user equipment used upon accessing a network in a wireless communication system, wherein the PMSI is assigned to a corresponding user equipment for V2X communication network access, the method comprising: receiving, from the V2X user equipment, a message to request a first V2X ticket that authenticates access authorization to the identifier in a serving network of the V2X user equipment, the message comprising information for a second V2X ticket to authenticate the access authorization to the PMSI in a home network of the V2X user equipment, transmitting, to a mobility management entity, MME, of the home network, the information on the second V2X ticket, receiving, from the MME of the home network, International Mobile Subscriber Identity, IMSI, of the V2X user equipment determined based on the information on the second V2X ticket, confirming a validity of the IMSI using a specific cryptographic key used to confirm the validity of the IMSI, and transmitting, to the V2X user equipment, the first V2X ticket and information on a temporary key used to encrypt the PMSI in the serving network based on the IMSI, wherein confirming the validity of the IMSI comprises: receiving, from the MME of the home network, the specific cryptographic key and specific cryptographic key information encrypted from the specific cryptographic key using a temporary key used to encrypt the PMSI in the home network, transmitting the specific cryptographic key information to the V2X user equipment, receiving, from the V2X user equipment, the IMSI of the V2X user equipment encrypted using the specific cryptographic key, and confirming whether the IMSI of the V2X user equipment received from the V2X user equipment is identical with the IMSI of the V2X user equipment received from the MME of the home network. receiving, from the V2X user equipment, a message to request a first V2X ticket that authenticates access authorization to the identifier in a serving network of the V2X user equipment, the message comprising information for a second V2X ticket to authenticate the access authorization to the PMSI in a home network of the V2X user equipment, transmitting, to a mobility management entity, MME, of the home network, the information on the second V2X ticket, receiving, from the MME of the home network, International Mobile Subscriber Identity, IMSI, of the V2X user equipment determined based on the information on the second V2X ticket, confirming a validity of the IMSI using a specific cryptographic key used to confirm the validity of the IMSI, and transmitting, to the V2X user equipment, the first V2X ticket and information on a temporary key used to encrypt the PMSI in the serving network based on the IMSI, wherein confirming the validity of the IMSI comprises: receiving, from the MME of the home network, the specific cryptographic key and specific cryptographic key information encrypted from the specific cryptographic key using a temporary key used to encrypt the PMSI in the home network, transmitting the specific cryptographic key information to the V2X user equipment, receiving, from the V2X user equipment, the IMSI of the V2X user equipment encrypted using the specific cryptographic key, and confirming whether the IMSI of the V2X user equipment received from the V2X user equipment is identical with the IMSI of the V2X user equipment received from the MME of the home network. receiving, from the MME of the home network, the specific cryptographic key and specific cryptographic key information encrypted from the specific cryptographic key using a temporary key used to encrypt the PMSI in the home network, transmitting the specific cryptographic key information to the V2X user equipment, receiving, from the V2X user equipment, the IMSI of the V2X user equipment encrypted using the specific cryptographic key, and confirming whether the IMSI of the V2X user equipment received from the V2X user equipment is identical with the IMSI of the V2X user equipment received from the MME of the home network.