To provide an assembling structure for an eye coupling preventing a drop of a packing 20 during conveyance and assembling work and having excellent efficiency of assembling work.

This assembling structure for the eye coupling is provided with a joint body 12 having an eyeball part 16, the packing 20 fitted to the eyeball part 16 and a bolt 30 fastened on a mating component Pt by penetrating through a bolt hole 18. A extension part 24b extended from an inner peripheral edge of a through-hole 24a along the inner peripheral wall of the bolt hole 18 is formed in a lower seal part 24 of the packing 20. On the inner peripheral wall of the extension part 24b, a female screw 24c into which a male screw 34 is screwed is formed. By screwing the male screw 34 of the bolt 30 into the female screw 24c, the packing 20 is strongly fitted to the joint body 12.