An adsorption refrigerator is effective device to reduce the global warming. However it is necessary to down size the adsorber to make it into wide use. To reduce the size of adsorption refrigerator, it is important to make simulation model which can calculate the performance of adsorber. In the simulation model, some parameters of the layer (thermal conductivity, gas diffusion coefficient and so on) have to be estimated from experimental data. In this paper, gas diffusion coefficient was measured using minute glass beads from those parameters. Then the data was compared to simulation results, and an equation that indicates the gas diffusion coefficients was derived.