A measured object mounting tool 2 for producing a three-dimensional shape data comprises a placing part 2b at the lower face of a cylindrical part 2a, an inclined part 2c at a boundary between the side face and the upper face of the cylindrical part 2a, and a pillar part 2d at the upper face of the cylindrical part 2a, where the pillar part 2d has a mounting part 2e at the upper face thereof, a three-dimensional coordinate other than the engaging portion 3a of a model 3 is produced by engaging the model of the dental prosthesis with the mounting part 2e of the tool 2 on a placing table 1; detecting a position where a received light amount is remarkably decreased to by a laser sensor detect a lower end of the inclined part 2c; and thereby calculating an upper end of the engaging portion 3a.