A horizontal universal joint comprising: a first joint member integrally formed by a frame insertion port and a female coupling port, the frame insertion port facing a horizontal direction, the female coupling port facing a vertical direction; and a second joint member integrally formed by a frame insertion port and a male coupling port, the frame insertion port facing the horizontal direction, the male coupling port facing the vertical direction, wherein: the female coupling port of the first joint member and the male coupling port of the second joint member are removably engaged via an elastic body, wherein the elastic body is disposed between the female coupling port 13 of the first joint member 11 and the male coupling port 23 of the second joint member 21, teeth rows (15, 25) are formed at an inner peripheral surface of the female coupling port and an outer peripheral surface of the male coupling port meshing with one another, and depending on meshing positions of both teeth rows (15, 25) when the male coupling port is inserted into the female coupling port, the horizontal direction where the frame insertion port of the second joint member faces relative to the frame insertion port of the first joint member is changeable, wherein the first joint member further includes an auxiliary frame insertion port integrally formed opposed to the female coupling port, and an auxiliary frame coupling pipe is removably engaged with the auxiliary frame insertion port, wherein a V-shaped leaf spring is pushed into the auxiliary frame coupling pipe. a first joint member integrally formed by a frame insertion port and a female coupling port, the frame insertion port facing a horizontal direction, the female coupling port facing a vertical direction; and a second joint member integrally formed by a frame insertion port and a male coupling port, the frame insertion port facing the horizontal direction, the male coupling port facing the vertical direction, wherein: the female coupling port of the first joint member and the male coupling port of the second joint member are removably engaged via an elastic body, wherein the elastic body is disposed between the female coupling port 13 of the first joint member 11 and the male coupling port 23 of the second joint member 21, teeth rows (15, 25) are formed at an inner peripheral surface of the female coupling port and an outer peripheral surface of the male coupling port meshing with one another, and depending on meshing positions of both teeth rows (15, 25) when the male coupling port is inserted into the female coupling port, the horizontal direction where the frame insertion port of the second joint member faces relative to the frame insertion port of the first joint member is changeable, wherein the first joint member further includes an auxiliary frame insertion port integrally formed opposed to the female coupling port, and an auxiliary frame coupling pipe is removably engaged with the auxiliary frame insertion port, wherein a V-shaped leaf spring is pushed into the auxiliary frame coupling pipe. the female coupling port of the first joint member and the male coupling port of the second joint member are removably engaged via an elastic body, wherein the elastic body is disposed between the female coupling port 13 of the first joint member 11 and the male coupling port 23 of the second joint member 21, teeth rows (15, 25) are formed at an inner peripheral surface of the female coupling port and an outer peripheral surface of the male coupling port meshing with one another, and depending on meshing positions of both teeth rows (15, 25) when the male coupling port is inserted into the female coupling port, the horizontal direction where the frame insertion port of the second joint member faces relative to the frame insertion port of the first joint member is changeable, wherein the first joint member further includes an auxiliary frame insertion port integrally formed opposed to the female coupling port, and an auxiliary frame coupling pipe is removably engaged with the auxiliary frame insertion port, wherein a V-shaped leaf spring is pushed into the auxiliary frame coupling pipe.