In this study, the effect of microscopic structure on mechanical characteristics of stretch fabrics were evaluated for reasonable design of sports wear. Stretch fabric shows anisotropic mechanical behavior because of its microstructural effect. In order to obtain the macroscopic mechanical characteristics of the fabric, uniaxial tensile tests were conducted. Also, the deformation of the yarn was recorded by the microscope video measurement system to investigate the effect of microscopic structure on the macroscopic mechanical characteristics. The recorded videos were analyzed with motion image analysis software TEMA (Photron Ltd.). From the analysis result, microscopic strain and the angle between warp and weft yarn were obtained. The microscopic behavior of stretch fabric was clarified comparing microscopic strain with macroscopic stress. Correlation coefficients about fitted curve parameter and yarn parameter are obtained.