A storage information update method, an image forming apparatus, a system for managing the image forming apparatus, and a mobile device are provided. The method is performed by an image forming apparatus to which at least one identification number is assigned, a storage configured to store the identification number of the image forming apparatus, and a terminal device communicable with the storage. The method includes acquiring, by the terminal device, the at least one identification number of the image forming apparatus and transmitting, by the terminal device, the received at least one identification number to the storage.