A joint apparatus includes a first fixed ring, a second fixed ring arranged spaced apart from the first fixed ring, an extension portion comprising a bar extending from the first fixed ring in a direction toward the second fixed ring and an end portion disposed at an end portion of the bar in the direction toward the second fixed ring, a first flexure extending from the second fixed ring in a direction toward the first fixed ring and supporting the end portion, and a second flexure extending from the second fixed ring in the direction toward the first fixed ring and supporting the end portion, the second flexure being disposed at an opposite side to the first flexure with respect to the extension portion.
