Abstract: In construction of an apparatus for innoxious disposal of medical wastes, the medical wastes containing meltable components such as plastic resins, and unmeltable components such as syringe needles and residues are thrown into a compression hopper and compressed under application of heat by piston operation into a compact cake. Sharp unmeltable components such as syringe needles are totally embraced by the meltable components such that they are not exposed outside the obtained cake, thereby removing the danger in subsequent handling of the cake. Pathogenic germs in the residues are killed during application of heat and the residues are fully evaporated due to heating in an evaporation dish arranged below the compression hopper.