A vehicle system includes: a vehicle platform including a first computer that controls traveling of a vehicle; an automated-driving platform including a second computer that controls automated-driving of the vehicle; a first network connecting the vehicle platform and the automated-driving platform; a second network connecting the vehicle platform and the automated-driving platform; a main power supply that supplies electricity required for communication in the first network; a sub-power supply that supplies electricity required for communication in the second network; and a communication interface that allows communication between the vehicle platform and the automated-driving platform to be performed by using any one of the first network and the second network.