The mutual diffusion coefficient of aqueous solutions with sugars of various molecular weight. obtained by drying experiment of the solution. was investigated for the effects of concentration. temperature and molecular weight of sugar. The mutual diffusion coefficient of dilute solution was correlated using Wilke’s diffusion factor. The concentration dependence was presented by linear relation of the logrithm of the diffusion coefficient vs. the sugar mole fraction regardless of temperature. The slopes of the linear relations were expressed by a power function of the molecular weight. From the linear relation. the activation energy was expressed also by linear relation of the sugar mole fraction. in which the slopes were expressed by the other power function of the molecular weight. The resultant estimation equation covers well for the temperature range 298-323 K and for the molecular weight range of sugars. from 180 for glucose to 6100 for maltodextrin.