An auxiliary elastic device for a joint protector is capable of producing auxiliary elasticity for human joints. The device includes a connecting body connected to a multiple of serially and pivotally coupled pivots, a through slot penetrated through the connecting body, and at least one stripe elastic rib movably installed in the through slot and capable of providing an elastic supporting force and an elastic restoring force when human joints are bent, so as to achieve the effect of reducing the burden of the joints.
