A safety information transmission method in a safety information transmission system constituted by a portable terminal (103, 105) and a plurality of vehicle-mounted terminals, comprising: a first step in which a first portable terminal transmits safety information to the vehicle-mounted terminal; a second step (S513, S707) in which the vehicle-mounted terminal stores the safety information received from the first portable terminal; a third step in which the vehicle-mounted terminal transmits the safety information to another vehicle-mounted terminal by a vehicle-to-vehicle communication; a fourth step (S515, S807) in which the vehicle-mounted terminal stores the safety information received from the other vehicle-mounted terminal by the vehicle-to-vehicle communication; and a fifth step in which any of the vehicle-mounted terminals transmits the safety information stored in the vehicle-mounted terminal to an information server via an access point in a case where the vehicle-mounted terminal 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 in a case where the vehicle-mounted terminal has become capable of communicating with the second portable terminal, further comprising: a step in which the vehicle-mounted terminal receives a disaster occurrence notification; a step in which the vehicle-mounted terminal distributes a disaster application program to the first portable terminal in response to the reception of the disaster occurrence notification; and a step in which the first portable terminal installs the disaster application program distributed from the vehicle-mounted terminal, wherein the transmission of the safety information from the first portable terminal to the vehicle-mounted terminal is performed via the disaster application program. a first step in which a first portable terminal transmits safety information to the vehicle-mounted terminal; a second step (S513, S707) in which the vehicle-mounted terminal stores the safety information received from the first portable terminal; a third step in which the vehicle-mounted terminal transmits the safety information to another vehicle-mounted terminal by a vehicle-to-vehicle communication; a fourth step (S515, S807) in which the vehicle-mounted terminal stores the safety information received from the other vehicle-mounted terminal by the vehicle-to-vehicle communication; and a fifth step in which any of the vehicle-mounted terminals transmits the safety information stored in the vehicle-mounted terminal to an information server via an access point in a case where the vehicle-mounted terminal 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 in a case where the vehicle-mounted terminal has become capable of communicating with the second portable terminal, further comprising: a step in which the vehicle-mounted terminal receives a disaster occurrence notification; a step in which the vehicle-mounted terminal distributes a disaster application program to the first portable terminal in response to the reception of the disaster occurrence notification; and a step in which the first portable terminal installs the disaster application program distributed from the vehicle-mounted terminal, wherein the transmission of the safety information from the first portable terminal to the vehicle-mounted terminal is performed via the disaster application program. a step in which the vehicle-mounted terminal receives a disaster occurrence notification; a step in which the vehicle-mounted terminal distributes a disaster application program to the first portable terminal in response to the reception of the disaster occurrence notification; and a step in which the first portable terminal installs the disaster application program distributed from the vehicle-mounted terminal, wherein the transmission of the safety information from the first portable terminal to the vehicle-mounted terminal is performed via the disaster application program.