The deposition rate of focused-ion-beam chemical-vapor-deposition (FIB-CVD) is much higher than that of electron-beam chemical-vapor-deposition (EB-CVD) due to factors such as the difference of mass between electron and ion. Furthermore, FIB-CVD has an advantage over EB-CVD in that it is more easily to make a complicated 3-dimensional nanostructures. Because, a smaller penetration-depth of ion compared to electron allows to make a complicated 3-dimensional nanostructures. For example, when we make a coil nanostructure with 100 nm linewidth, electrons with 10-50 keV pass the ring of coil and reach on the substrate because of large electron-range (over a few µm), so it is very difficult to make a coil nanostructure by EB-CVD. On the other hand, as ion range is less than a few ten-nm, ions stop inside the ring. Three-dimensional nanostructure fabrication using FIB-CVD has following advantages. (1) As a beam diameter of FIB is 5nm, 3 D nanostructures with a few ten nm can be fabricated by FIB. (2) 3D nanostructures made of metal, semiconductor, and insulator etc. can be fabricated by using various source gases. Three-dimensional nanotechnology using FIB can be widely applied to electronics, mechanics, optics, and biology. We have demonstrated the fabrication of free-space-nanowiring, electrostatic nano-actuator, bio-injector and electrostatic nano-manipulator by using FIB-CVD.