The recrystallization of amorphous cellulose at various relative humidities was studied to clarify the relation between the amount of adsorbed water in cellulose and the molecular motion by the DSC method. The initial recrystallization kinetics of amorphous cellulose at various relative humidities were observed on the basis of the exothermic peak between 380° and 470°K in a DSC curve. The recrystallization occurred easily by conditioning at higher than 80% R.H., but hardly by conditioning at lower than 65% R.H. These facts suggest that the conformation of cellulose seems to be easily changeable if cellulose has a moisture regain which is approximately comparable to capillary water. When the Avrami equation was applied to the slope of calorific value versus conditioning time at higher than 80% R. H., it also appeared that the mode of recrystallization growth of amorphous cellulose exposed to water vapor is one-dimensional.