In the conservation of museum objects, detection of chemical changes as they first occur is of great importance. The author has tried to develop ways to detect slight change of cultural properties made of such organic substances as silk, urushi and Japanese paper by the two methods; chemiluminescence counting method and electron spin resonance method. In this report, some experiments were done in evaluating the deterioration of silk, paper and urushi objects. It was revealed that each method has both merits and demerits respectively but that these methods have possibilities to get the significant progress in conservation of organic cultural properties.