1. An image forming apparatus that executes a job by using a job history, the image forming apparatus comprising: a buffering unit that buffers an operation code specific to the image forming apparatus and an operating condition corresponding to the operation code; an interpreter unit that encodes an operation code, which has been buffered in the buffering unit, to a text code and decodes original operation code from the text code; and a shared-history creating unit that creates a shared job history that describes encoded text code and an operating condition corresponding to the encoded text code in association with a sequence of operation codes; and a re-executing unit that reads a shared job history created by other image forming apparatus and re-executes operation codes in read shared job history in order of being decoded.