To suppress oppression of a transfer band for data in a tandem type image formation apparatus.

In a tandem type image formation apparatus, a control part including an arithmetic processing circuit and a main memory and an image processing part including an image processing circuit and an inter-drum delay memory are connected to each other through an I/F, and the image processing circuit performs control to calculate the capacity of raster data to be stored to correct a delay based upon a selected form size and a physical distance of a photosensitive drum, to compare the capacity of the raster data to be stored with the capacity of the inter-drum delay memory, to calculates the number of lines of the raster data which can be stored in the inter-drum delay memory when the capacity of the raster data to be stored is larger than the capacity of the inter-drum delay memory, and to store raster data in the inter-drum delay memory by as much as the calculated number of lines and also to save raster data of lines which cannot be stored in the inter-drum delay memory in a main memory through the I/F.