To provide a screw hole structure capable of stably fastening a screw by setting the screw so as to stand upright relative to a screw hole in temporary insertion of the screw, and to improve the workability of the screw fastening.

The screw hole structure is comprised of a guide hole 3a having a larger diameter than the diameter of a screw thread, and the screw hole 3b screwing the screw. Ribs 5, coming in contact with the inserted screw 1 in long plate shapes expanding in the depth direction in parallel with the depth direction of the guide hole 3a, or being screwed-in by the screw, are protrusively formed on the internal peripheral surface of the guide hole 3 and arranged at four even intervals in the internally circumferential direction of the guide hole 3a.