To provide a sealing member which facilitates construction of a sealing structure at a construction site and does not spoil the water-tightness of a joint part even when a width of the joint is changed after the seal member starts serving.

The sealing member 1 inserted between adjacent panels P, P comprises a pair of trunk parts 15, 15 facing each other in an adjoining direction of the panels P, P, and a waist part 10 connecting base ends of the trunk parts 15, 15 to each other. A pair of leg parts 20, 20 are formed on the waist part 10 in a manner of extending toward the end faces of the panels P, P, respectively. The trunk parts 15, 15 and the leg parts 20, 20 are inserted between the panels P, P while being deformed inward, and are brought into contact, under pressure, with the end faces of the panels P, P, respectively, by the restoring force.