Orally disintegrating tablets(ODT) are collapsed by saliva without the assistance of water and facilitates the taking of drugs. However, the increase of tablet strength promotes the increase of oral disintegration time of ODT. The purpose of this study was to clarify the significant properties of diluent powders in ODT to obtain both high tablet strength and short disintegrating time simultaneously. We focused on water (saliva) permeability into tablets and swelling behavior, and attempted to control them by the selection of various binders as well as the surface modification of hydrophobic powders. As a result, the increase of tablet porosity by using high binding binders to maintain high tablet strength and the surface hydrophilic modification on the hydrophobic particles, promoted water permeability. Moreover, the swelling ability of disintegrants provided a greater contribution than their wicking ability to obtain shorter disintegrating time.