Tapping depth measuring device

The utility model relates to the technical field of screw thread hole measuring devices, and provides a tapping depth measuring device. The tapping depth measuring device comprises a tightened device which is tightened in a tapping screw thread hole, and a scale which matches the tightened device. The tightened device is provided with a screw thread end and a handheld end. The screw thread end is provided with an outer screw thread which matches an inner screw thread of the screw thread hole. A center hole is arranged in the tightened device. The scale is provided with a reading end and an extending end. The reading end is provided with a reading scale region. The extending end matches the center hole of the tightened device. The extending end extends from one side, which is located on the handheld end, of the center hole to the side of the screw thread end, and runs out to the bottom of the screw thread hole. According to the utility model, the scale is used to read the numerical difference between the tight