Abstract: The present invention relates to a filling device for introducing pre-foamed, post-expandable thermoplastics into molds for the production of moldings from plastic foams, especially from pre-foamed polystyrene foam, for example Styropor or Styrocell, in which the pre-foamed plastic is introduced in granular form into the mold by reason of a pressure difference existing between the stock container for the plastic granules and the mold and/or introduction of injected air. The filling device essentially consists of a cylindrical piston case with a lateral feed pipe for the plastic granules and a piston which is movable in the longitudinal direction within the cylindrical piston, for closing the mold inlet orifice after filling has taken place. The filling device according to the invention is characterized by a movable shut-off sleeve, which, by means of a spring, blocks the supply of granules when the piston has passed the feed pipe in the direction towards the mold.