An apparatus for introducing molding sand into a mold space defined by a pattern plate (1) having a pattern, a flask (2) placed on the pattern plate (1) for surrounding the pattern, and a filling frame (3) placed on the flask (2) and for compacting the molding sand in the mold space. The apparatus includes a sand hopper (10) having an inlet pipe (7) for introducing a first airflow at a low pressure (0.05 to 0.18 MPa) and compressed air thereinto from an upper part thereof, and a plurality of separated nozzles (17) at a lower portion thereof for blowing and introducing the molding sand held in the sand hopper into the mold space by the first airflow. First and second chambers (11 and 12) supply a second airflow under a low pressure (0.05 to 0.18 MPa) and compressed air to the molding sand in the sand hopper (10) to fluidize the molding sand. Vertically movable, multi-segmented squeeze feet (16) are mounted on the lower portion of the sand hopper (10) at various locations, each of which is adjacent to a side of each nozzle, for compacting the molding sand in the mold space. In the sand hopper (10), a cutter (14) is provided to mill sand balls contained in the fluidized molding sand within the sand hopper (10).