An image information coding system is disclosed which analyzes an input image and which can make exact image quality control even when the input image has been subjected to coding and decoding in the previous stage. A coded image information decoding unit decodes coded image information and outputs both code attribute information and decoded image information. An image information dividing unit divides the decoded image information into rectangular regions consisting of a predetermined number pixels and outputs divided image information. An image information analyzing unit measures a statistic of the divided image information while making reference to the code attribute information and outputs image quality control information taking coding and decoding conditions in the previous stage into account. A coding parameter control unit decides a coding parameter on the basis of the image quality control information, and an image information coding unit encodes the divided image information using the coding parameter and outputs the thus-coded information.