A jig 20 that is installed on a device for measuring dimensions of a workpiece 10 based on images obtained by taking pictures of the workpiece 10 with a camera K includes a chuck mechanism 50 holding the workpiece K, a first rotation drive mechanism 80 that rotates the chuck mechanism 50 around a predetermined first rotation axis A, a first base 30 holding the first rotation drive mechanism 80, a second rotation drive mechanism 40 that rotates the first base 30 around a second rotation axis B orthogonal to the first rotation axis A, and a second base 21 holding the second rotation drive mechanism 40. The first base 30 has an opening 31A in the area around the first rotation axis A such that the workpiece 10 held by the chuck mechanism 50 is seen from the back of the first base 30 through the opening 31A.