The purpose of this project is to investigate the strength of nano-structures. First, we put on the focus to the mechanics of crack initiation from the free interface edge in nano-meter scale structures. We propose an experimental method for evaluating the initiation crack strength. The interface crack initiation in the structures is governed by the singular stress field, and the criterion is prescribed by the stress intensity parameter. Then, a compression test for a single crystal column with diameters of several tens of nanometers is conducted with an In-situ transmission electron microscope (TEM) observation. The nanocolumn has a high yield stress and a specific deformation behavior different from those of a bulk single crystal.