Unearthed <irushi</i> filmy materials are usually accompanied with inorganic contaminants such as metal oxides, silicates, and the like, which may interfere in the identification of films based on their infrared (IR) spectra. This paper shows that the combination of a physical treatment for removing major inorganic contaminants utilizing their density differences from <irushi</i> in a carbon tetrachloride-ethanol mixture, and a subsequent chemical treatment with hydrofluoric acid to remove the remaining inorganic contaminants consisting mainly of silicates is an effective pretreatment for the identification of <irushi</i> films based on their IR spectra. For example, two unearthed filmy materials were identified as <irushi</i> films by their IR spectra obtained after the pretreatment mentioned above. The completeness of the pretreatment can be confirmed by the fact that the IR absorbances at 2,850 and 2, 920 cm^-1 are greater than that at 3,400 cm^-1 and the absorbance at 1,000 ~ 1,100 cm^-1 is less than that at 1,600 ~ 1,720 cm^-1. -- AATA