Abstract: A chair for reducing a load on the buttocks and the waist, and, to a chair (100) includes a seat (110) and a backrest (130) and further comprising a spacer (120) protruding upward from the rear end of the seat (110), wherein the bottom of the backrest (130) is provided on the top of the spacer (120) so as to be tiltable rearward, and the point at which the angle of the backrest (130) is adjusted with respect to the spacer (120) corresponds to a point (P) at which the lumbar of a user body sitting on the seat (110) is curved inward.

Abstract: A support for a chair includes: a base plate (110); support plates (120, 130), of which one sides are rotatably coupled to the base plate (110); and a first hinge (150) which connects the base plate (110) and the support plates (120, 130) to be rotatable, wherein the base plate (110) is supported by a seat portion (11) of a chair (10) and the support plates (120, 130) are supported by a back portion (12) of the chair (10) while the base plate (110) and the support plates (120, 130) are unfolded at a first maximum unfolding angle (?1m) and support the upper body of a user.

Abstract: A chair for reducing a load on the buttocks and the waist, and, to a chair (100) includes a seat (110) and a backrest (130) and further comprising a spacer (120) protruding upward from the rear end of the seat (110), wherein the bottom of the backrest (130) is provided on the top of the spacer (120) so as to be tiltable rearward, and the point at which the angle of the backrest (130) is adjusted with respect to the spacer (120) corresponds to a point (P) at which the lumbar of a user body sitting on the seat (110) is curved inward.