To provide a chair with high durability even in a simple configuration.

The chair includes an elastic frame 8 which can be bent and deformed and is constituted so that a tip end 82 can receive a load applied to a back rest 6 when the back rest 6 is backwardly tilted, on which the tip end 82 and the base end 81 are rotatably mounted. The elastic frame 8 changes so that the distance between the base end 81 and the tip end 82 gets closer as the back rest 6 is backwardly tilted, obtaining elastic deformation with larger curvature. Therefore, an appropriate resilient repulsive force can be given to the back rest 6.