To perform fitting and fitting release by simple operation.
A fitting structure includes a first fitting part 13 with an insertion hole 13a and a second fitting part 32 inserted in the insertion hole 13a and fitted in the first fitting part 13. In the first fitting part 13, a first groove part 21 corresponding to a part with a center angle around a center axis A2 in a female screw less than 90° is formed only in a first area 13c corresponding to a part with a center angle around a center axis A1 in the inner peripheral surface 13b of the insertion hole 13a less than 90°, and a second groove part 22 corresponding to another part with the center angle around the center axis A2 in the female screw less than 90°, and moreover, opposed to the first groove part 21 is formed only in a second area 13d corresponding to another part with the center angle around the center axis A1 in the inner peripheral surface 13b of the insertion hole 13a less than 90°, and moreover, opposed to the first area 13c. In the second fitting part 32, a male screw 41 engaging with the first groove part 21 and the second groove part 22 is formed throughout the whole circumference of the outer peripheral surface 32b.
HAGA NATSUKO
NOMURA KAYOKO