PURPOSE: To efficiently mold minute pieces by feeding the predetermined necessary and enough amount of the minute pieces to a product cavity.

CONSTITUTION: The molding device concerned consists of a mold 28 having a cavity 36 and an introducing port 30 and an overflow passage 38, both of which communicate with the cavity, a feed passage 26 having an on-off valve 22, which communicates with the introducing port 30, and delivery passages 44 and 48, which are opened to the introducing port and have an on-off valve 46. Under the condition that the pressure in the introducing port is detected at the position between the cavity 36 and the delivery passages 44 and 48, slurry, which is prepared by mixing solvent and minute pieces so as to be turned into supercritical fluid, is introduced under high pressure from the feed passage through the introducing port in the cavity 36 and, at the same time, the solvent in the slurry is delivered through the delivery passages and, when detection pressure becomes equal to the predetermined value, the on-off valve 22 is closed and the on-off valve 46 is opened.