PURPOSE: To improve the grinding accuracy by grinding a work roller first by a grinding liquid at the upstream side in the roller rotating direction in the vicinity of a contact line of the work roller and a backup roller, and subsequently, pouring the grinding liquid into said contact point.

CONSTITUTION: A nozzle 3 is placed at the upstream side in the roller rotating direction in the vicinity of a contact line of a work roller 1 and a backup roller 2, and under the nozzle 3, an abrasive guide 4 is provided to as to contact the work roller 1. When a grinding liquid which has mixed an abrasive is injected to high pressure water from the nozzle 3, the grinding liquid collides with the surface of the work roller 1 and polishes its surface. The grinding liquid is retained on the abrasive guide 4, and led into the contact line of the work roller 1 and the backup roller 2 by a rotation of the roller 1. In this state, the secondary grinding of the work roller 1 and the backup roller 2 is executed.