To obtain a parallel image processor for efficiently carrying out an algorithm for image processing in which processing load varys.

The parallel image processor is provided with a image area assignment means 2 and a processing load calculation means 8. The image area assignment means 2 assigns a processing area and a processing restriction quantity to respective processors and when reassignment is requested from a processor, the means 2 reassigns an area whose assignment is requested as an unprocessed area. The processing load calculation means 8 calculates the processing load in an object image area about the assigned processing area by the respective processors, and instructs to process it a corresponding image processing execution means 9 about a range which does not exceed a designated processing restricted quantity. In the case of exceeding the processing restricted quantity, the means 8 requests reassignment of the area of restriction over to the means 2.