CHAIR

Provided is an unprecedented chair in which movement of a seat by using a rolling surface can be smoothly performed.The chair includes an upper base unit 31 and a lower base unit 32 facing each other, and a seat 1 that is provided in the upper base unit 31 and swings when the upper base unit 31 rolls with respect to the lower base unit 32, and the upper base unit 31, which is at least one of the upper base unit 31 and the lower base unit 32, includes a rolling surface 312a being curved. In the chair, a region having a different curvature exists in a part of the rolling surface 312a, and an elastic member 33 is interposed between the region having the different curvature and a corresponding region of an opposing surface.