A location information registration method, comprising: transmitting, by a mobile communication terminal, a location registration request signal of making a registration request of location information of the mobile communication terminal, to a first mobile communication network over which the mobile communication terminal can communicate; transmitting, by a first mobile management node of the first mobile communication network, the location registration request signal to a first subscriber server connected with the first mobile communication network, when the first mobile management node connected with the first mobile communication network receives the location registration request signal; transmitting to the mobile communication terminal, by the first mobile management node, a first location registration response signal in which a predefined value indicative of a cause of rejecting the registration request of the location information is set, when the first mobile management node determines that a registration of the location information of the mobile communication terminal cannot be completed; transmitting, by the mobile communication terminal, the location registration request signal of the mobile communication terminal to a second mobile communication network based on the predefined value, when the mobile communication terminal receives the first location registration response signal in which the predefined value is set and when there is the second mobile communication network over which the mobile communication terminal can communicate; and carrying out, by the mobile communication terminal and based on the predefined value, a first location registration operation of retransmitting the location registration request signal to the first mobile communication network, when there is not the second mobile communication network or when it is determined that a location registration of the mobile communication terminal in the second mobile communication network is not completed. transmitting, by a mobile communication terminal, a location registration request signal of making a registration request of location information of the mobile communication terminal, to a first mobile communication network over which the mobile communication terminal can communicate; transmitting, by a first mobile management node of the first mobile communication network, the location registration request signal to a first subscriber server connected with the first mobile communication network, when the first mobile management node connected with the first mobile communication network receives the location registration request signal; transmitting to the mobile communication terminal, by the first mobile management node, a first location registration response signal in which a predefined value indicative of a cause of rejecting the registration request of the location information is set, when the first mobile management node determines that a registration of the location information of the mobile communication terminal cannot be completed; transmitting, by the mobile communication terminal, the location registration request signal of the mobile communication terminal to a second mobile communication network based on the predefined value, when the mobile communication terminal receives the first location registration response signal in which the predefined value is set and when there is the second mobile communication network over which the mobile communication terminal can communicate; and carrying out, by the mobile communication terminal and based on the predefined value, a first location registration operation of retransmitting the location registration request signal to the first mobile communication network, when there is not the second mobile communication network or when it is determined that a location registration of the mobile communication terminal in the second mobile communication network is not completed.