An object of this invention is to improve convenience to a user when starting up an engine remotely, without detracting from safety with respect to vehicle theft. A remote startup device has an engine startup control unit, which starts the engine in response to a startup instruction signal, and an engine running control unit, which decides, after the engine has been started up, whether to continue or to stop running of the engine based on prescribed conditions. The engine running control unit continues running of the engine when detecting a key at the time of unlocking of a door of the vehicle and at the time of ignition action, and stops running of the engine when not detecting a key either at the time of the door unlocking or at the time of the ignition action, to thereby secure safety with respect to theft.