PURPOSE: To perfectly restrain growth of lug parts on both end sides of a grinding roll at the time of carrying out surface grinding work of a long metal plate material by making a radius of a central part at the time of abrasion larger than a lug part radius after grinding and removing the lug part of the grinding roll and making its difference smaller than thickness of the long metal plate material.

CONSTITUTION: Both end side lug parts of an abrased grinding roll 1, that is, a part where a long metal plate material does not pass is ground by driving a lug removing grinding tool driving motor 16 by way of giving a movement order to lug removing grinding tool lateral movement devices 21, 21 so that head end parts of grinding tools 14, 14 for grinding roll lug removal come to the both end side lug parts of the abrased grinding roll 1. At this time, when it is specified that a central part radius at the time when a central part of the grinding roll 1 is abrased due to grinding work of the long metal plate material 3 is R7, a lug part radius after grinding and removing a lug part of the grinding roll 1 is S, and thickness of the long metal plate material 3 is (t), S is smaller than R7 and a difference of R7 and S is smaller than (t).