To provide a joint structure, a work execution method therefor and a joint material, by which in case of laying a joint structure between the existing caissons, it can be accurately positioned in the end face of the caisson.

A joint material 10 is so constructed that a pair of plate members 16 are fixed to each other by fixing bars 27, 28 and the plate members 16 are provided with a suspension locking member 29. While the attitude of the joint material 10 is controlled by operating a suspension means such as a rope, a rod or the like locked in the member 29, the joint material is suspended by a crane, its anchoring part 19 is disposed on the caisson end face, and the projected upper end part of the plate member 16 is hit to drive the projected lower end 16a of the plate member 16 in the ground at the bottom of water. Subsequently, the projected upper end is cut off at need, and the upper end of the plate member 16 is welded to the fixed plate 24 fixed to the top 1a of the caisson 1.