This study relates to the cleaning and reuse of metal masks used in the process of manufacturing organic EL displays, which belong to the next-generation display. Supercritical carbon dioxide was used as the solvent to wash those masks. In this study, the solubility of organic compound by supercritical carbon dioxide was measured, and modeling of solubility was completed. Focusing attention on the fact that the solubility is almost at the same level as that of RED60 dye, which is under development toward practical application, it was verified whether it was possible to thoroughly wash the mask, using mimic metal masks.