Apparatus and method

The present invention addresses the problem of providing a device and method for improving the security level of a CAN. The present invention is provided with: a first interface unit which is connected to a first controller area network (CAN) bus; the second interface part is connected with a second CAN bus; and a control unit that, when the transmission of the CAN frame has started, executes an operation of specifying the first CAN bus or the second CAN bus, the dominant state of which has been detected first after the end of the arbitration, as the CAN bus to which the transmission source device of the CAN frame is connected. 本发明的课题在于提供使CAN的安全等级提高的装置和方法。该装置具备：第一接口部，与第一CAN(Controller Area Network)总线连接；第二接口部，与第二CAN总线连接；以及控制部，在开始了CAN帧的发送的情况下，执行将在仲裁的结束后首先被探测到显性状态的第一CAN总线或者第二CAN总线确定为该CAN帧的发送源装置连接的CAN总线的动作。