The present invention relates to a device wherein an elastic body which is shaped to conform to the curvature of the back of a human body (spine), and which is repulsive against bending and tensioning, is worn on an upper body part with upper/lower wearing belts； bending force occurring due to the weight of the upper part of the human body during a bending/stretching exercise is stored as repulsive force of the elastic body； and the repulsive force is recycled when the human body is stretched, thereby reducing consumption of force required for bending/stretching. The present invention is characterized in that a composite elastic body or a leaf spring is designed in a block type such that bending repulsive force from the leaf spring and tension of a separate coil spring are combined, making it possible to adjust the total bending repulsive force； the composite elastic body or leaf spring is shaped like a coil such that the resulting integrated elastic body has bending/tensioning/rotating repulsive force； the integrated elastic body can respond to bending, tensioning, and twisting resulting from a physical exercise； and the action of the elastic body can be improved/enhanced by external force. The present invention relates to a bending/stretching capability improving device worn on a human body, which reduces a load on the waist in an equivalent amount to the combination of an acting repulsive force from an elastic body and an action of a tension winch during a bending/stretching exercise or when a weight is lifted, and which accordingly reduces damage to the waist.
