The invention relates to an office chair having a foot part (8) and having a lying function, comprising gripper jaws (10) at the free end of the foot part (8) for gently holding the feet in position. The foot part (8) can be pivoted up, the connected seat surface (6) can be moved toward a vertical plane by means of a cam control, and the backrest (7) can be moved toward a horizontal plane. The distance of the gripper jaws (10) from the seat surface (6) can preferably be increased by means of a motor (12) having an electric spindle drive. As soon as the foot part (8) pivots up beyond the horizontal plane toward a vertical plane, the gripper jaws (10) can be raised such that stretching forces act on the spinal column of a person. The position change of the seat surface (6) together with the backrest (7, 7') and the foot part (8) with respect to a rigid floor frame (1) is achieved by a guide having at least one rail (2) curved in a U-shape, which rail runs along the sliding pieces (roller pairs 3, 4).