An upright posture retainer for upper body includes two upright retaining frames, and an adjusting device connected with the upright retaining frames and adjusted a distance between the upright retaining frames; wherein each of the upright retaining frames includes a resilient longitudinal retaining frame extended longitudinally and tending to recover an original upright state under stress, a shoulder retaining member and a leg retaining frame, wherein the shoulder retaining member is extended from an upper end of the resilient longitudinal retaining frame so as to form a shoulder contacting space, wherein the leg retaining frame is extended from an lower end of the resilient longitudinal retaining frame and transversely extended to form a leg retaining space, thereby contacting with the front of the human leg; wherein the adjusting device is fixed to the resilient longitudinal retaining frames of the upright retaining frames and supports the rear of upper body.