Disclosed is a gear including a resettable metallic glass. The gear of the present disclosure includes, as a base material, a resettable metallic glass, wherein the resettable metallic glass includes at least one metal element selected from each of (a) the group consisting of Ti, Zr, and Hf and (b) the group consisting of Fe, Co, Ni, Cu, and Zn, and further includes at least one metal element to maximize the complexity in the thermodynamic enthalpy of mixing among constituent elements, thereby including multiple resetting cores in various atomic-scale cluster forms in an amorphous matrix, leading to a structure with maximized structural complexity.