To generate a large quantity of fine mist in an aerosol generating device used in a jet type nebulizer.

A gas lead-in tube 6 is disposed for leading in a gas upward from the center on the bottom of a container 1 of the aerosol generating device, and a cylindrical body 9 with a narrow aperture 8 at the center on the upper face covers the outside of the gas lead-in tube 6. A cylindrical slit whose width is in the range from 2.0 to 0.3 mm is formed between the outer wall 10 of the gas lead-in tube 6 and the inner wall 12 of the cylindrical body 9 almost over the whole height of the outer wall 10 of the gas lead-in tube 6. A baffle 11 is disposed with a distance from the aperture 8 on the upper face of the cylindrical body 9, and a convex face R is formed on the baffle and a concave face 14 is formed on the upper surface of the cylindrical body 9. The concave face 14 passes the aperture 8 and is concentric with the convex face R, with a larger curvature than that of the convex face R. A curved-face slit is formed between the convex face R and the concave face 14.