A joint, comprising: a housing formed in a cylindrical shape having a predetermined length and having a hollow inner space formed therein and an insertion hole formed at one longitudinal side thereof to allow the hollow inner space to be open to an outside of the housing; a slot (172a, 172b) having a predetermined width extending in a circumferential direction of the housing and a predetermined length extending in a longitudinal direction of the housing is formed in the housing; characterized by a first shaft support inserted into the housing through the insertion hole; a second shaft support inserted into the housing through the insertion hole and provided between the insertion hole and the first shaft support, and a pair of coupling shafts (174, 176), one of the pair of coupling shafts (174, 176) provided at each of the first shaft support and the second shaft support to rotatably couple the first shaft support or the second shaft support to the housing, wherein the coupling shaft provided in the second support includes: a rotary shaft rotatably inserted into the slot and rotatably coupled to the housing; and a stopper formed to protrude from an outside of the rotary shaft and whose position inside the slot is changed according to rotation of the rotary shaft, the stopper being provided in the slot so that the stopper interferes with an inner wall of the housing formed by the slot at a predetermined position. a housing formed in a cylindrical shape having a predetermined length and having a hollow inner space formed therein and an insertion hole formed at one longitudinal side thereof to allow the hollow inner space to be open to an outside of the housing; a slot (172a, 172b) having a predetermined width extending in a circumferential direction of the housing and a predetermined length extending in a longitudinal direction of the housing is formed in the housing; characterized by a first shaft support inserted into the housing through the insertion hole; a second shaft support inserted into the housing through the insertion hole and provided between the insertion hole and the first shaft support, and a pair of coupling shafts (174, 176), one of the pair of coupling shafts (174, 176) provided at each of the first shaft support and the second shaft support to rotatably couple the first shaft support or the second shaft support to the housing, wherein the coupling shaft provided in the second support includes: a rotary shaft rotatably inserted into the slot and rotatably coupled to the housing; and a stopper formed to protrude from an outside of the rotary shaft and whose position inside the slot is changed according to rotation of the rotary shaft, the stopper being provided in the slot so that the stopper interferes with an inner wall of the housing formed by the slot at a predetermined position. a rotary shaft rotatably inserted into the slot and rotatably coupled to the housing; and a stopper formed to protrude from an outside of the rotary shaft and whose position inside the slot is changed according to rotation of the rotary shaft, the stopper being provided in the slot so that the stopper interferes with an inner wall of the housing formed by the slot at a predetermined position.