An electronic control unit is mounted on a vehicle, and includes a reception unit that receives a data signal transmitted via a transmission path mounted on the vehicle; an environmental information acquisition unit that acquires environmental information of the vehicle; and a determination unit that determines the state of the transmission path, in which the reception unit includes an equalizer that compensates for the data signal, the equalizer calculates a compensation parameter for compensating for the data signal, and the determination unit determines the state of the transmission path based on the compensation parameter and the environmental information.