To provide a jointing structure in which even if a screw member is loosened, the screw member does not fall off and positioning of the screw member and a screw hole can be made easily, and screwing work is excellent.

This is the jointing structure in which the screw member 4 which penetrates through an insertion hole 31 of a first member 3 is screwed into a screwing hole 21 of a second member 2 in the state the first member 3 and the second member 2 are superposed. A screw portion 42 having a screw thread and a neck portion 43 which is positioned between this and a head portion 40 of the screw member 4 and has no screw thread and has an outer diameter d smaller than the screw thread diameter e of the screw portion 42 are provided at the stem 41 of the screw member 4, the inner diameter a of the insertion hole 31 of the first member 3 is made larger than the outer diameter d of the neck portion 43 and smaller than the screw thread diameter e of the screw portion 42, and the screwing hole 21 of the second member 2 is constituted of a guide portion 22 which has an inner diameter b larger than the above screw thread diameter e and has a length L1 longer than the length L2 of the screw portion 42 at the entrance side and a screwing portion 23 which extends from the guide portion 22 and into which the screw portion 42 of the screw member 4 is screwed.

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