In an on-vehicle system, on-vehicle device and gateway are connected via a first network, and the gateway and relay are connected via a second network. The relay performs open-close control of a gate, using a TAS standard of Ethernet TSN. The gateway receives first and second packets including given data, generates a third packet including the first and second packets, and sends the third packets at the transmission timing that is a timing the gate is placed in from closed state to open state to the relay. The relay receives the third packet from the gateway. The relay switches timing to transfer data, for each type of data, and transfer the third packet to the other relay, during a period in which the gate for the type of data is in an open state.