A chair, especially an office chair, includes a seat that is fastened on a base support unit, a backrest that includes a back lower region and an upper shoulder region and is fastened to a back support, the back support being supported by the base support unit in a manner permitting rotation about an inclination axis. The shoulder region is connected to the back support in a manner permitting inclination about a shoulder axis and is hinge-connected to a back lower region at a lumbar region, and the back lower region further extends along a chair element so that when the shoulder region is inclined about the shoulder axis, an angle of the shoulder region relative to the back lower region is changed.