A frame memory holds a reference frame that is to be referenced for motion detection for a target block of a coding target frame in motion images. A motion compensation unit that includes a motion detecting unit and a motion compensated prediction unit. The motion detecting unit detects the motion of said target block by repeated motion estimation with reference to said reference frame stored in said frame memory, and the motion compensated prediction unit performs motion compensation processing for the target block using information on the detected motion. A coding unit that performs coding processing for the subtraction image and the information on the detected motion and thereby creates a coded stream. The motion compensation unit includes a pre-reading memory which stores pixel data beforehand, where said pixel data is part of pixel data in said reference frame, which is to be frequently referenced for motion detection, and which has been transmitted from said frame memory.