To perform an output even to an image forming device coping with only old encryption (decryption) algorithm without a problem when executing an encrypted secure job in a system wherein a plurality of image forming devices are connected to a network.

This image forming system comprises: a means encrypting and decrypting confidential output information; a means transmitting and receiving the encrypted confidential output information; a means deciding whether or not the encrypted confidential output information can be decrypted by the decryption means of the system itself; a means transmitting a decryption function of the system itself; a means registering equipment capable of decrypting the encrypted confidential output information, and connected to the network, when the encrypted confidential output information cannot be decrypted by the decryption means of the system itself; a means transmitting the encrypted confidential output information to the other equipment; a means performing the decryption and reencryption in the other equipment connected to the network; and a means outputting the encrypted confidential output information.