The glycerol, known as a hydrophillic plasticzer, was used for the improvement of brittle wool keratose films. The effect of glycerol contents, which were added to a soluble fraction of oxidized wool keratose, was examined on the structure and mechanical properties using circular dichroism spectropolarimeter, FTIR, X-ray diffractometer, and Instron. Circular dichroism showed that the addition of glycerol above 20% content induced the conformational change of keratose solution from ${alpha}$-helix, and ${eta}$-sheet structure. FTIR spectra and X-ray diffraction pattern also gave the evidence of conformational changes and showed that the relative intensity of characteristic ${eta}$-sheet conformation peak of keratose film was increased with the addition of glycerol. The mechanical properties of keratose film were drastically changed in the case of above 16% of glycerol added. Especially, the elongation at break was increased from 1.1% to 18.2%, indicating the improvement of film flexibility. The mechanical properties are related to the moisture regain of keratose film; breaking strength and strain were decreased and increased, respectively, with an increase of moisture regain.