To realize a high density and homogeneous compaction by filling up powdered materials in a compacting rubber mold in uniform density under the condition that the crosslinking of the powdered materials is avoided from developing by a method wherein the flexible compacting mold is made to pulse by passing a pressure medium therethrough at filling the powdered materials in the compacting mold.

During the filling of powdered materials from a powdered material feeding box 16 in a compacting rubber mold 4, a pressure medium in a pressure vessel 1 is vibrated periodically. Thus, the compacting rubber mold 4 is made to periodically pulse from its side surface through a pressurizing rubber mold 6 arranged on the outer periphery of the compacting rubber mold 4. As a result, the crosslinked portion among the powdered materials in the compacting rubber mold 4 is broken, resulting in annulling the uneven density due to crosslinking and, at the same time, the powdered materials are supplied from the powdered material feeding box 16, resulting in uniformly filling the compacting rubber mold 4. Thus, the powdered materials can be highly densely and homogeneously compacted.