1. A VOXEL model coordinate decision processing method of making a structure analysis of a modeled analysis object, using a VOXEL method, the method comprising: a first step of calculating a volume error between an actual volume of the analysis object and a volume of a VOXEL model generated in a certain coordinate system; a second step of rotating the analysis object around an axis of the coordinate system to make a VOXEL division of the analysis object and generating a VOXEL model of a newly rotated analysis object; a third step of calculating a new volume error between the actual volume of the analysis object and the volume of the rotated VOXEL model; a fourth step of comparing a previous volume error and a new volume error and selecting the VOXEL model with smaller volume error; and a fifth step of repeating the second to fourth steps a predetermined number of times to adopt the coordinate system of the VOXEL model finally selected as the VOXEL coordinates.