A chair comprising a support structure bearing a seat and a backrest, in which the backrest comprises a bearing portion and a connecting portion for connection to the support structure, in which the backrest is tiltable rearwards relative to a resting position under a rearwards thrust applied by the user and elastically returns to the resting position when the rearwards thrust ceases. The rearwards tilting of the backrest is formed in part by an elastic detonation of the bearing portion and in part by a displacement of at least a part of the connecting portion relative to the support structure.