A vehicle-to-vehicle communication device mounted to a subject vehicle with a traveling control device is provided. The vehicle-to-vehicle communication device includes a communication portion, a connection transmission process portion, a connection control signal obtain portion, a connection signal obtain portion, and a connection control signal transmission process portion. The communication portion receives and transmits a signal between the subject vehicle and a preceding vehicle, and between the subject vehicle and a follower vehicle. The connection transmission process portion transmits a connection request signal. The connection control signal obtain portion obtains a connection control signal. A convoy travel control device includes the vehicle-to-vehicle communication device and the traveling control device. The traveling control device periodically outputs a first instruction and a second instruction to the vehicle-to-vehicle communication device.