A transmitting device is mountable in a vehicle. A first detector detects entry of another vehicle into vicinity of a vehicle mounted with the transmitting device. A second detector detects stabilization in a relationship between the other vehicle and the vehicle after the first detector detects the entry. A recording unit records a vehicle behavior of the vehicle from timing when the first detector detects the entry of the other vehicle to timing when the second detector detects the stabilization in the relationship between the other vehicle and the vehicle. A transmitter transmits the vehicle behavior recorded in the recording unit after the second detector detects the stabilization.