A joint member includes a base member and a key member. The base member includes: a cylindrical portion having a first opening at one end and second opening at other end that is inserted into the through-hole; a flange portion that is formed around a first opening of the cylindrical portion; hook members that are connected to opposite inner walls of the cylindrical portion; a rib that is formed on at least one of the hook members and extends toward the first opening. The key member includes: a pushing portion that is insertable into the cylindrical portion through the first opening, butts against the rib portion to rotate the hook member toward the second opening. When the pushing portion is inserted in the cylindrical portion, the flange portion and the hook member sandwich the packing members, and the ribs close the opening at the other end of the cylindrical portion.