A support assembly according to an embodiment of the present invention includes a support rotatably disposed with respect to a frame, a jack rotatably connected with respect to the support on a side opposite to a rotation center of the support, and a support heel disposed on a lower surface side of the support to make contact with a member connected to a key, wherein the support is configured of a first main body portion, a bent portion, a second main body portion, and a jack support portion from the rotation center side of the support toward a rotation center side of the jack, and the second main body portion is disposed on a side closer to the key than the first main body portion by the bent portion which couples the first main body portion and the second main body portion.