A mouthpiece (150A) has an aerosol lead-out channel (104), an aerosol lead-outopening (105), and an exhalation discharge opening (106). The lead-out channel(104) includes a first channel (104A) extending upward, a second channel (104B)extending obliquely forward from the first channel (104A), and a corner channel(104C) for connecting the first channel (104A) and second channel (104B) of thelead-out channel (104). The mouthpiece (150A) has a curvature section (153)formed by curving that portion of the first channel (104A) wall surface whichcrosses the center line of the first channel (104A). The exhalation dischargeopening (106) is provided in a wall surface defining the second channel (104B),at a position circumferentially displaced from the wall surface portion at whichthe curvature section (153) is provided. In the mouthpiece and an inhalator withthe mouthpiece, although an exhalation valve and, in addition, an inspirationvalve are eliminated, leakage of aerosol from a pressure regulation openingand the exhalation opening is prevented independent of how they are used.
