<p>An inhalator including an inhalator body including a powder receiving chamber for receiving a powder, an air-powder mixture reservoir for temporarily storing an air-powder mixture flowing from the powder receiving chamber, and a diluent air passage for introducing a diluent air into the air-powder mixture reservoir. The air-powder mixture is formed within the powder receiving chamber when an air is introduced into the powder receiving chamber. The air-powder mixture within the air-powder mixture reservoir is admixed with a diluent air introduced thereinto through the diluent air passage. The diluted air-powder mixture is discharged from an air-powder mixture outlet into a user's oral or nasal cavity. A powder composition for inhalators includes at least two kinds of fine particles different in particle diameter. <IMAGE></p>