To provide a treating device capable of efficiently disposing of a wet waste with a low load on environments.

This ventilation-type grinding/drying device comprises a cylindrical disposal container which is rotatable and hermetically contains the waste to be disposed of and stirs it, a blade which is arranged in the container and rotates, centered around an axis in parallel with the rotary shaft of the container and further, stirs/grinds the waste falling by its own weight after being conveyed and moved by the rotation, an arc-like plate which is positioned below leaving a slight gap on the outside of a track of a blade tip and grinds the waste using a constriction stress and a centrifugal force generated between the blade tip and the waste and further, has many small holes for the ground waste to pass through, an air supply means for supplying air into the disposal container and an air discharging means which discharges the air present in the container to its outside.