Au-coated nanosprings were fabricated by a combination of focused-ion-beam chemical vapor deposition (FIB-CVD) and sputter coating. A Au thin layer was successfully coated onto nanosprings fabricated by FIB-CVD. To confirm the mechanical motion, the authors performed an optical microscopy observation in which the Au sputter-coated nanosprings were able to expand and contract mechanically, as flexibly as macroscale springs. The measured spring constants of the Au-coated nanosprings ranged from 0.27 to 16 N/m, depending on the coil-section diameter. In addition, through the quantitative measurement of the mechanical characteristic of the nanosprings, the authors estimated that Au-coated nanosprings had a sufficient mechanical strength, which is useful for application in nanoelectromechanical system with three dimensions. (c) 2006 American Vacuum Society.