1. An image forming apparatus comprising image forming means for forming an image based on image data on a recording carrier, said image forming apparatus comprising: pattern image storing means for storing plural pattern image data, wherein each of the pattern image data is for forming plural pattern images on a recording carrier; folding procedure accepting means for accepting a folding procedure for folding the recording carrier; pattern selection accepting means for accepting a selection of said plural pattern image data stored in said pattern image storing means; position accepting means for accepting a forming position of an image based on the pattern image data whose selection is accepted by said folding procedure accepting means on the recording carrier folded according to the folding procedure accepted by said folding procedure accepting means; and image data generating means for generating a folding procedure image data for forming an image showing the folding procedure accepted by said folding procedure accepting means on the recording carrier, and pattern forming image data for forming an image based on the pattern image data whose selection is accepted by said pattern selection accepting means at said forming position accepted by said position accepting means on the recording carrier folded according to the folded procedures accepted by said folding procedure accepting means as one set of image forming information, wherein said image forming means forms on the recording carrier an image based on the folding procedure image data and/or the pattern forming image data included in one set of the image forming information generated by said image data generating means.