A 3D spring array device includes: a fixed body having an internal space therein; a moving body positioned in a center of an x-y-z orthogonal coordinate system in the internal space, wherein the moving body is configured to be fastenable to the end effector of the mechanical impedance estimating robot; and a first spring, a second spring, a third spring, a fourth spring, a fifth spring, a sixth spring, a seventh spring, and an eighth spring and configured to connect the fixed body to the moving body in the internal space.