To surely stop water by means of a simple structure at a connection between front and rear concrete casings when the casings are used as a water channel; to easily deal with relative displacement between the front and rear concrete casings by means of the flexibility of a joint structure; to facilitate maintenance by making the joint structure replaceable.

A joint structure for underground structure is used in a method of construction whereby a plurality of underground structure formed of concrete casings 4 and the like are connected in tandem and buried. A connecting member 14 made of rubber which serves as a joint in the form of an elongate band is used to interconnect the inner surfaces of the connecting ends of the underground structure located in upper and lower positions. A projecting curved part 14a is formed at the center of the joint along its longitudinal direction.