A gateway device connected to a bus of a first network through which a frame of a first type is transmitted using the bus in accordance with a first communication protocol, which is a CAN, controller area network, protocol, and a second network through which a frame of a second type is transmitted in accordance with a second communication protocol, which is an Ethernet protocol and which is different from the first communication protocol, wherein the first and second networks are vehicle networks and wherein the gateway device is connected to an Ethernet cable included in the second network the gateway device comprising: a reception unit configured to sequentially receive the frame of the first type from the bus, wherein the frame of the first type is a data frame including a CAN-ID and, in a data field, the data; and a determination unit configured to determine whether to transmit data regarding the frame of the first type received by the reception unit to the second network; and a transmission unit configured to transmit, to the second network, the frame of the second type including data regarding a plurality of frames of the first type determined by the determination unit to be transmitted to the second network by outputting the frame of the second type to the cable, wherein the frame of the second type is an Ethernet frame including an Ethernet header and a payload, and wherein the transmission unit transmits the frame of the second type while arranging, in the frame of the second type, the data regarding the plurality of frames of the first type determined by the determination unit to be transmitted to the second network in order of predetermined priority levels of the CAN-IDs based on CAN-IDs of the frames of the first type. a reception unit configured to sequentially receive the frame of the first type from the bus, wherein the frame of the first type is a data frame including a CAN-ID and, in a data field, the data; and a determination unit configured to determine whether to transmit data regarding the frame of the first type received by the reception unit to the second network; and a transmission unit configured to transmit, to the second network, the frame of the second type including data regarding a plurality of frames of the first type determined by the determination unit to be transmitted to the second network by outputting the frame of the second type to the cable, a determination unit configured to determine whether to transmit data regarding the frame of the first type received by the reception unit to the second network; and a transmission unit configured to transmit, to the second network, the frame of the second type including data regarding a plurality of frames of the first type determined by the determination unit to be transmitted to the second network by outputting the frame of the second type to the cable, wherein the frame of the second type is an Ethernet frame including an Ethernet header and a payload, and wherein the transmission unit transmits the frame of the second type while arranging, in the frame of the second type, the data regarding the plurality of frames of the first type determined by the determination unit to be transmitted to the second network in order of predetermined priority levels of the CAN-IDs based on CAN-IDs of the frames of the first type.