The present invention provides a joint-assisting device comprising: a wearing part worn on the waist of a body connecting parts provided at both sides of the lower part of the wearing part so as to be fixed around the hip joints rotating parts worn on the body at the upper side of the wearing part so as to rotate while moving integrally with the body during bending or stretching motions of the upper body or knees, coupled to the connecting parts by rotary shafts provided at one side thereof, having rotary pieces formed in a fan shape so as to rotate around the rotary shafts, and having guide grooves formed along the arcs of the rotary pieces and an elastic part of which the upper part is coupled to the connecting part so as to reduce the weight applied to the lumbar or joints when the rotating parts rotate, and which comprises an elastic member embedded in a state in which the upper end or lower end thereof is fixed, a connecting cable connecting the elastic member and the rotary piece and moving in a state, in which the connecting cable is settled in the guide groove, when the rotating part rotates, and elastic fixing bands provided at the lower part of the elastic part so as to be worn on the thighs.
