Crystallization behavior of water sorbed into various non-water soluble polymers was examined by temperature-variable Fourier transform infrared spectroscopy (TV-FTIR) and differential scanning calorimetry (DSC). In general understanding of the sorbed water at low water content on the basis of DSC, all of the sorbed water has been considered to be non-freezing water. However, their TV-FTIR spectra clearly demonstrated the existence of the change in state including recrystallization of water by revapor deposition, which was vapor deposition (sublimation) during heating. Recrystallization of the sorbed water has been proposed to be devitrification and be a characteristic of biocompatible polymers. Recrystallization, however, was also observed in non-biocompatible polymers and recrystallization observed in the biocompatible polymer was not devitrification but revapor deposition.