Provided is a screw hole inspection device with high inspection accuracy. The incomplete thread portion of a gauge portion 5 of a screw gauge 1 is removed, a phase positioning portion 8 for positioning a tip-side start point 7 of a complete thread to a predetermined phase when the screw gauge 1 is mounted on a rotating shaft portion 2 is provided at a fastening portion 6 of the screw gauge 1 thatis to be fastened to the rotating shaft portion 2, and a phase positioning engaging portion 9 that is to be engaged with the phase positioning portion 8 is provided at the rotating shaft portion 2. The depth of a screw hole 4 to be inspected is measured on the basis of the rotation speed and thread pitch of a rotating shaft feed moving mechanism 18 that, by screwing, feeds and moves the rotating shaft portion 2 in the screw hole approaching direction in which the screw hole 4 is approached, the rotating shaft portion 2 being rotated by a rotary drive portion 3, and on the basis of the amount of movement of a separation direction moving portion 23 in the screw hole separation direction, and then the depth of the screw hole 4 is calculated.