Die-casting tends to generate casting defects during the production process. In an attempt to reduce the casting defect, we carried out the compression test of ADC12 aluminum alloy die castings in cylinder-shaped at high temperature. To evaluate the efficiency of reduction of casting defects, first the nondestructive tests were carried out by X-ray computed tomography. Next, three-dimensional images were obtained from X-ray computed tomography images by using "VOXELCON". From these three-dimensional images, the shape of the casting defects was observed and the reduction state was evaluated. The casting defects in the specimens become less when the compression strain of specimens becomes higher. We concluded that, applying compression load is effective to reduce casting defects.
