To form a maintaining groove at the same time of piercing at the time of dental technical work by arranging plural rotation preventing maintaining groove (maintaining hole) formers around a center drill so as to constitute a piercing device for setting pins.

In the piercing device for setting pins to be used in dental technique, in order to simultaneously execute piercing and the forming of the maintaining groove which were executed in different processes before, a center drill 3 to be grasped by a drill chuck 4 at the center position of a base bottom board 1 and plural such as four rotation preventing maintaining groove formers 2 are arranged around this center drill 3. The former 2 is position-adjusted to make its tip project a little from the board 1 to assemble to the board 1. Thus, after setting a model at an optional position, when lowering the piercing device for setting pins from an upper most position, a pin hole and the maintaining groove are simultaneously worked.