A gateway device connected to one or more networks (10, 20, 30, 40, 50, 60, 70) used by a plurality of electronic control units (100, 101, 200, 201, 300, 301; 400, 401, 500, 600, 700) for communication, the gateway device comprising: a reception unit configured to receive a frame; and a transfer unit (906, 905, 901) configured to transfer one or more frames to a destination network, which is one of the one or more networks (10, 20, 30, 40, 50, 60, 70); wherein the transfer unit (906, 905, 901) is further configured to remove or add verification information, which is used to verify the frame, from or to content of the frame received by the reception unit and to transfer a frame resulting from the removing or adding of said verification information to the destination network; wherein, if a first frame including verification information received by the reception unit satisfies a certain removal condition for removing the verification information, the transfer unit (906, 905, 901) is configured to perform the transfer by generating a second frame including information based on the content of the first frame other than the verification information and transmitting the second frame to the destination network, and wherein, if the first frame including verification information received by the reception unit does not satisfy the certain removal condition for removing the verification information, the transfer unit (906, 905, 901) is configured to generate a second frame including the information based on the content of the first frame other than the verification information and verification information generated using a key shared with an electronic control unit connected to the destination network and to transmit the second frame to the destination network. a reception unit configured to receive a frame; and a transfer unit (906, 905, 901) configured to transfer one or more frames to a destination network, which is one of the one or more networks (10, 20, 30, 40, 50, 60, 70); wherein the transfer unit (906, 905, 901) is further configured to remove or add verification information, which is used to verify the frame, from or to content of the frame received by the reception unit and to transfer a frame resulting from the removing or adding of said verification information to the destination network; wherein, if a first frame including verification information received by the reception unit satisfies a certain removal condition for removing the verification information, the transfer unit (906, 905, 901) is configured to perform the transfer by generating a second frame including information based on the content of the first frame other than the verification information and transmitting the second frame to the destination network, and wherein, if the first frame including verification information received by the reception unit does not satisfy the certain removal condition for removing the verification information, the transfer unit (906, 905, 901) is configured to generate a second frame including the information based on the content of the first frame other than the verification information and verification information generated using a key shared with an electronic control unit connected to the destination network and to transmit the second frame to the destination network.