Abstract: A powder processing apparatus of the fluidized bed type wherein air is blown into a cylindrical container through its bottom to perform various treatments while keeping powder in the container in fluidized condition. Air fed in through an opening in the bottom surface of the container is introduced into a rotating hollow frusto-conical body and is allowed to blow out in the centrifugal direction from an air diffusion clearance defined between the skirt end of the frusto-concial body and the bottom surface of the container, thereby forming a fluidized bed of powder. The portion of the bottom surface around the opening rises and/or a member made of air-permeable material is installed in the opening in the bottom surface to prevent passage of powder; this arrangement, coupled with the air current blowing out of the air diffusion clearance, prevents entry and hence flow-out of powder.