PURPOSE: To obtain a foaming unit, which eliminates a roll-in of unfoamed grains, by successively placing preheated material beads in a mold form and further bringing these beads into contact with heated gas from a delivery pipe, arranged in the mold form, to promote foaming.

CONSTITUTION: A land creating device is constituted of a mold form 1, Y-type input pipe 2, porous plate 3, delivery pipe 4, hoses 5, 6, pressure regulating valve 7, pressure pump 8 and a boiler 9 or the like. The input pipe 2 and a conveyer hose 10 are connected, and they are connected to a connection port 1a of the mold form 1 by providing a material tank 11 of material beads 14 and the conveyer hose 10 for conveying these beads, in the outside. Next, a required amount of material beads 14 is heated in the input pipe 2, prefoamed and deposited on the porous plate 3 in a condition without unfoamed grains, and on the other hand, steam of about 100°C is delivered from the delivery pipe 4 at a flow rate of about 2m3 per minute. In this way, a foaming unit of uniform quality can be obtained.