A measured object mounting tool for producing three-dimensional shape data includes a placing part at a lower face of a cylindrical part, an inclined part at a boundary between a side face and an upper face of the cylindrical part, and a pillar part at the upper face of the cylindrical part. The pillar part has a mounting part at the upper face thereof. A three-dimensional coordinate other than the engaging portion of a model is produced by engaging the model of the dental prosthesis with the mounting part of the tool on a placing table, detecting a position where a received light amount is remarkably decreased with a laser sensor to detect a lower end of the inclined part, and thereby calculating an upper end of the engaging portion.