To provide a valve having an insulating structure capable of enhancing earthquake resistance by increasing joining strength against an external force.

A joint 4 comprises an annular first joint body 6 welded to a valve box body 32 and having an insertion hole, and a cylindrical second joint body 7 with one end portion thereof inserted in the insertion hole. The second joint body 7 has a flange portion 8 on one end portion thereof. A stepped portion 9 to regulate the movement of the flange portion 8 in the drawing direction A is formed on the first joint body 6, and an annular fixing member 13 disposed facing the stepped portion 9 from the side opposite to the flange portion 8 with respect to the first joint body 6 is housed over the second joint body 7. The fixing member 13 and another tubular body 3 are welded to the second joint body 7. A space between the first joint body 6 and the second joint body 7 and a space between the first joint body 6 and the fixing member 13 are insulated with insulating material 14.