We report the dynamic infrared spectroscopic studies on segmented poly(urethaneurea). In this study, we take into consideration not only the dynamic dichroic difference spectra but also the dynamic average absorption spectra, in order to detect dynamic change in concentration of hydrogen bondings. As a result, the similarity in shapes of spectra between the static and dynamic dichroic difference and the great difference of spectra between the static and dynamic average absorbances are obtained. It is concluded that stress along the urea carbonyl bonds, but not along the polymer chains, takes an important role on the negative orientation of the hard segment domains.