A technique based on atomic force microscopy (AFM) for dynamic measurement of mechanical properties of a single polymer chain was proposed. AFM cantilever was mechanically oscillated at approximately 10 kHz during stretching process. By this technique, we could quantitatively estimate elongation-dependent changes of stiffness and viscosity of a single chain itself with using a phenomenological model. The solvent effect on the viscosity in low extension regions was investigated. It was ensured that the viscosity under 10 kHz perturbation was attributed to monomer-solvent friction. Viscosity quantization corresponding to consecutive detachments of polymer chains was also observed.