Provided is a distributed type image forming system which reduces storage capacity of server. An encryption addition part encrypts a document data for outputting by pull print with a symmetric key, encrypts the symmetric key by a public key of a user who is permitted to output of the document data, and adds the encrypted symmetric key to the document data. A division part divides document data into a job block and a user block having the symmetric key encrypted by the public key of the user and generates the blockchain of document data. A key decoding part decrypts the symmetric key included in the user block with the secret key of the user. A block acquisition part acquires other blocks from preserving apparatuses. A document reproduction part packs each block to reproduce document data. An output part outputs the reproduced document data.