To grind various subjects to be ground in ideal states by moving a grinding cylinder to a vertically accurate position by an extremely simple mechanism.

In this grinding device, the gap of a narrow ring slit 5 formed between the grinding cylinder 1 and a rotary member 3 provided at the bottom of a grinding gap 4 is adjusted by raising/lowering the grinding cylinder 1 having a grinding opening 2 at the center by a vertical mechanism. The cylinder 1 has plural female screw holes extending vertically on the outer periphery. Plural screwed rods are provided in vertical postures on a pedestal 16 at the positions to be screwed into the female screw holes of the cylinder 1 so that the rods can be rotated but can not be moved vertically. The plural screwed rods are connected to a driving mechanism 11 to be rotated together while synchronizing with a mechanism 11. The cylinder 1 is moved vertically while keeping the horizontal posture by the plural screwed rods rotated by the mechanism 11.