This study focuses on permeability in the molding process of fiber reinforced plastics. Microscopic resin permeation behavior is governed by the capillary number, which is assumed to be dependent on temperature and pressure. We experimentally evaluated the temperature and pressure conditions at which capillary numbers became identical when different resins were impregnated into an identical glass cloth. We observed that when the capillary numbers were identical, different resins exhibited almost identical permeability values.