A joint realizing higher rigidity without increasing the wall thickness provided with a base part 12, a pair of side parts 14, 14 extending from the two end parts of the base part 12 in the first direction D1 to the same side in the second direction D2 vertical to the first direction D1, the pair of side parts 14, 14 being formed with fastening holes 14H at the center in a third direction D3 vertical to both the first direction D1 and second direction D2, and a closed part 16 formed between the pair of side parts 14, 14 as an extended region of the base part 12 and pair of side parts 14, 14 at least at one end in the third direction D3.

A joint provided with a base part 12, a pair of side parts 14, 14 extending from the two end parts of the base part 12 in the first direction D1 to the same side in the second direction D2 vertical to the first direction D1, the pair of side parts 14, 14 being formed with fastening holes 14H at the center in a third direction D3 vertical to both the first direction D1 and second direction D2, and a closed part 16 formed between the pair of side parts 14, 14 as an extended region of the base part 12 and pair of side parts 14, 14 at least at one end in the third direction D3.