In order to examine the deformation behavior of a silicon nano-helix grown by the glancing angle deposition technique, tensile experiment was conducted with in-situ scanning electron microscope observation. An isolated nano-helix was prepared by removing neighboring nano-helices using a removable probe, and the top end was connected to a loading tip with an electron beam curing adhesive. The nano-helix was monotonically deformed up to fracture with a large elastic elongation due to the helical shape. It was found that the deformation stiffness of the nano-helix is governed by the geometry. Moreover, the yield stress was evaluated to be τ_γ = 550〜563 MPa.