A medicine administering device for nasal cavities, comprising a capsule holding section formed with a capsule containing powder-state medicine. An air supply section is connected to the lower end of the capsule holding section and formed with an air supply passage which is in communication with the capsule accommodating chamber. A branched passage section is connected to the upper end of the capsule holding section and has an air flow passage in communication with the capsule accommodating chamber. The air flow passage is bifurcated to form first and second outlet passage portions which are arranged to form a generally Y-shape. First and second medicine passages are formed such that air from the branched passage section flows therethrough to carry the medicine in the capsule into right-side and left-side nasal cavities of a patient. The first and second passages are respectively in communication with the first and second outlet passages of the branched passage section. First and second spraying holes are respectively in communication with the first and second medicine passages, the medicine from the first medicine passage and the medicine from the second medicine passage being sprayed respectively from the first and second spraying holes. The first and second spraying holes respectively have first and second axes which are separate from each other by a distance ranging from 12 to 25 mm.