An evaluation aid is used as a phantom (imitation lesion) when a digital X-ray dynamic image thereof is taken and evaluated for image qualities for X-ray absorption parts having different X-ray absorption ratios. The evaluation aid contains a fixed plate (plate-like body) including a plurality of regions having different X-ray absorption ratios; a rotating disk (movable body) having a plurality of wires (wire rods), the rotating disk capable of rotating (moving) with respect to the fixed plate so that the plurality of wires traverse X-ray with which the fixed plate is irradiated; and a driving motor (driving portion) which rotates (moves) the rotating disk with respect to the fixed plate. It is preferred that thicknesses and/or constituent materials of the plurality of regions of the fixed plate are different from each other, so that these regions have the different X-ray absorption ratios.