To improve the capacity and the efficiency by increasing the engagement angle while maintaining the strength of a roller for compression or pulverization.

Two rollers having a plurality of ridge-shaped projecting parts are engagement-rotated with a space therebetween so that the rollers are not brought into contact with each other, and an object is passed through between the rollers for compression or pulverization. The projecting parts have an isosceles-triangular section, and the apex angle thereof is preferably 90°. Since the object is pressed by inclined surfaces of the ridge-shaped projecting parts, the strength and the capacity are increased compared with the case when circular or gear-shaped rollers are used.