Chair having a movable seat

The chair has a simple structure in which a seat can follow a free movement of a seated person in front-rear, left-right, and diagonal directions, a burden from an operation by which the seated person balances his or her load can also be reduced, and a movement by which the seated person changes his or her posture stably and continuously can be suitably supported. The chair includes a movement mechanism 3 that causes an upper base unit (31) to swing in a direction of 360 degrees with respect to a lower base unit (32), and a seat 1 attached to the upper base unit (31). The chair further includes a damper mechanism (DM) that may operate by following a movement in a direction of 360 degrees, as a mechanism separate from the movement mechanism (3), at a position connecting the upper base unit (31) and the lower base unit (32).