To provide equipment for inter-vehicle communication capable of performing an appropriate inter-vehicle communication in accordance with the degree of congestion.

The equipment for inter-vehicle communication performs an inter-vehicle communication by a CSMA (carrier sense multiple access) system. The higher the degree of congestion of the inter-vehicle communication is, the lower a transmission output of the inter-vehicle communication is, whereby narrowing the transmission range of each vehicle and lowering the degree of congestion of the inter-vehicle communication. The number of vehicles that succeed in transmission increases to realize an appropriate inter-vehicle communication.