This is a brief study on the influence of fumigation (using mixed gas of methyl bromide and ethylene oxide) on old paintings. Fumigation is principally used to prevent biological damage of objects. Thirteen objects, including old colored map from Choson Dynasty and some paintings, were selected for this research. Before and after fumigation, color measurements were made and pH value were measured. The result is that fumigation did not affect on discoloration of colored area and acidity of paperr, as far as the standard of application (such as concentration of gas, exposing time and etc.) of fumigation was kept.