To obtain fine silicon dioxide powder which is suitable as e.g. a filler for various resin compositions and has high bulk density by efficiently increasing the bulk density in a short time by grinding with centrifugal force and simultaneously compressing silicon dioxide powder.

The objective silicon oxide is produced using a crusher provided with a main shaft that revolves at a high r.p.m., and a plural number of countershafts which rotates around the main shaft. On the outer circumference of the countershafts, several-millimeter-spaced gaps are made, and to the gaps a number of ring-shaped grinding media that revolve eccentrically around are fitted with a play, so that, when the main shaft is revolved at a high velocity, the ring-shaped grinding media are moved to the radial direction by a depth of the gap, are pressed to the inside surface of the casing by centrifugal force, take the fed silicon dioxide powder into the clearance between the grinding media and the inside surface of the casing, and grind and compress the silicon dioxide powder, thereby enabling the bulk density of the silicone dioxide powder from 20-40g/l to 80-300g/l in 5-120sec.