Waterglass was selected as an inorganic binder for use in solidification by drying, and a packed bed of glass particles wetted lightly with aqueous solution of the binder was solidified by microwave drying. The drying experiment was performed with a constant volume of binder in the dried sample, and the initial liquid fraction (the volume ratio of the binder solution to the void in the packed bed) was changed in the range from 0.10 to 0.35. Changes in the drying rate and the surface temperature were measured. As a result, all of the drying rate curves against the mean moisture content with the different initial liquid fraction partly overlapped in the low range of moisture content and a master curve was obtained, while no master curve was found for the surface temperature curves against the mean moisture content. The result for waterglass binder with an initial liquid fraction of less than 0.15 was compared with the result for gelatin as an organic binder in the authors' previous study. The maximum drying rate of the waterglass binder was more than double that of the gelatin binder.