Deformation behavior of the segmented block copolymers was studied with synchrotron small-angle X-ray scattering (SAXS) and Fourier transform infrared spectroscopy (FTIR) methods. Polyurethanes used in this work consist of 4,4'-methylene-bis(phenyl isocyanate) and butanediol as a hard segment, and poly(tetramethylene oxide) of various molecular weights as a soft segment. As expected, the deformation of the domain structure that is macroscopically isotropic before the drawing was anisotropic. Depending on the initial orientation of the hard domains, the deformation behavior was observed to be characteristically different. Whereas the hard domains oriented along the deformation direction underwent the extension of the domain separation distance at the low draw ratio, the perpendicular ones showed the shear compression. Further drawing was found to cause the breakup of the hard domains, followed by the formation of fibril structure oriented along the deformation direction. Based on SAXS and FTIR results, a model is proposed to explain the deformation behavior of the various domains and segments of the segmented block copolymers. By quantitatively analyzing the conformation of the soft segment during the deformation process, the model proposed has been consolidated.