An electronic control unit configured to communicate through a bus in accordance with a CAN, Controller Area Network, protocol, the electronic control unit comprising: a reception unit configured to receive one or a plurality of data frames; and characterized by: a verification unit; wherein in a case where the reception unit receives the one or plurality of data frames and the one or plurality of data frames includes an identifier relating to data used for calculation for obtaining the message authentication code indicating authenticity of transmission content, the verification unit is configured to select the data used for the calculation for obtaining the message authentication code in accordance with the identifier included in the one or plurality of data frames received and to perform a process for verifying the message authentication code, and in a case where the reception unit receives the one or plurality of data frames and the one or plurality of data frames does not include an identifier relating to data used for calculation for obtaining a message authentication code indicating authenticity of transmission content, the verification unit is configured not to perform a process for verifying the message authentication code. a reception unit configured to receive one or a plurality of data frames; and characterized by: a verification unit; wherein in a case where the reception unit receives the one or plurality of data frames and the one or plurality of data frames includes an identifier relating to data used for calculation for obtaining the message authentication code indicating authenticity of transmission content, the verification unit is configured to select the data used for the calculation for obtaining the message authentication code in accordance with the identifier included in the one or plurality of data frames received and to perform a process for verifying the message authentication code, and in a case where the reception unit receives the one or plurality of data frames and the one or plurality of data frames does not include an identifier relating to data used for calculation for obtaining a message authentication code indicating authenticity of transmission content, the verification unit is configured not to perform a process for verifying the message authentication code. a verification unit; wherein in a case where the reception unit receives the one or plurality of data frames and the one or plurality of data frames includes an identifier relating to data used for calculation for obtaining the message authentication code indicating authenticity of transmission content, the verification unit is configured to select the data used for the calculation for obtaining the message authentication code in accordance with the identifier included in the one or plurality of data frames received and to perform a process for verifying the message authentication code, and in a case where the reception unit receives the one or plurality of data frames and the one or plurality of data frames does not include an identifier relating to data used for calculation for obtaining a message authentication code indicating authenticity of transmission content, the verification unit is configured not to perform a process for verifying the message authentication code.