Chair

A chair includes: a leg 1; a seat 2; and a front-back support mechanism 4. The front-back support mechanism 4 is provided at a seat receiving part 50 directly supported by the leg 1, and the front-back support mechanism includes: a wavy plate 56 provided to horizontally extend from vertical walls 51 of the seat receiving part 50 and having mound-shaped surfaces 57, 58 each convexly curved upward; and followers 53, 54 provided at front-back support bodies 52 as supported parts and configured to move relative to the mound-shaped surfaces 57, 58 while contacting the mound-shaped surfaces 57, 58. The wavy plate 56 is associated with the followers 53, 54 such that a movement end inclines downward when the seat 2 moves from a neutral position in accordance with a relative movement between the mound-shaped surfaces 57, 58 and the followers 53, 54.