A safety information transmission method includes a step wherein a first portable terminal transmits the safety information to the vehicle-mounted terminal, a step wherein the vehicle-mounted terminal stores the safety information received from the first portable terminal, a step wherein the vehicle-mounted terminal transmits the safety information to another vehicle-mounted terminal by a vehicle-to-vehicle communication, a step wherein the vehicle-mounted terminal stores the safety information received from the other vehicle-mounted terminal by the vehicle-to-vehicle communication, and a step wherein any of the vehicle-mounted terminals transmits the safety information stored in the vehicle-mounted terminal to an information server via an access point when the vehicle-mounted terminals has reached a communication possible area of the access point, or transmits the safety information stored in the vehicle-mounted terminal to a second portable terminal when the vehicle-mounted terminal has become capable of communicating with the second portable terminal.