Single carbon fiber (CF)-embedded thermoset epoxy resin (EP) and thermoplastic polycarbonate (PC) specimens were prepared to clarify the interfacial interaction between CF and a matrix polymer and the deformation behavior of the carbon fiber and a matrix polymer. Stress−strain curves of EP and PC samples including and excluding CFs showed yields at approximately 70 MPa. In situ polarized high-speed camera images of the samples revealed the effect of CF on stress propagation. Moreover, the retardation of the fiber/polymer interface was large and that of PC was higher than that of EP. Microbeam small/wide-angle X-ray scattering measurements revealed that the orientation of the polymer chains near the CF and the turbostratic structure of the CFs occurred for both EP and PC; craze formation was suppressed because of CF during the deformation process for PC.