A folding chair has a frame having first and second front legs and first and second rear legs. A back rest is operatively pivotally connected to the rear legs. A seat is slidingly connected to the first and second front legs and pivotally connected to the back rest, thereby enabling the angle of the backrest relative to the rear leg to be adjustable as the seat slides toward and away from the front legs.

The object of the invention is a convertible, dual function chair for sitting and kneeling, which gives the possibility of changing the position and relieving the spinal column during a prolonged work in a sitting position.

The dual function chair for sitting and kneeling is equipped with a movable backrest and headrest support, shaped in the lower part in such a way that its displacement changes the size of the chair simultaneously vertically and horizontally. It is also equipped with a sliding-rotating-returning or a sliding-returning backrest device, which makes it follow the user's back and support it accurately at every angle of inclination of the backrest when tilting the backrest. It is also equipped with a headrest connected to the headrest arm through a rotary-sliding mechanism, which rotationally connects with the backrest support, and has a specially shaped five-star base, in which the arms, apart from the fragment above the wheels, are maximally flattened and located as low as possible above the ground.