An inhalant medicator comprises a medicator body having a granular medicine accommodation chamber and an inhalant port, and air passageways disposed in the medicator body and communicating the inhalant port via the granular medicine accommodation chamber to the atmosphere for supplying granular medicines into the inhalant port. Also provided is a granular medicine diffusion means located downstream of the granular medicine accommodation chamber for efficiently diffusing the granular medicines. A cylindrical adapter 10 is detachably installed in the inhalant port 9. The granular medicine diffusion means comprises a granular medicine diffusion chamber 11 formed in the adapter, an adapter inlet passageway tangentially radially extending from the circumference of the diffusion chamber 11 for creating turbulent flow in the diffusion chamber, and an adapter outlet passageway intercommunicating the diffusion chamber and the inhalant port and having a diametrically-enlarged outlet passage portion, for good dispersion of the granulated medicines flowing out of the diffusion chamber into the inhalant port.