PURPOSE: To prevent incomplete grinding, and to improve productivity without damaging a steel pipe in eliminating a coating of a coated steel pipe by grinding the coating of the coated steel pipe by means of a grinding brush rotated at a high speed.

CONSTITUTION: A coated steel pipe 30 coated by a coating 32 is placed on turning rolls 33, 33, and a raising/lowering base 5 is moved to the required level by jacks 6. That is, the center level of a grinding brush 12 is set to the center height of the coated steel pipe 30. Next, a second traveling truck 8 is advanced by a cylinder 9. A motor 14 is started to rotate the grinding brush 12. Simultaneously, the turning rolls 33, 33 are rotated at a low speed. The coated steel pipe 30 is rotated in the direction opposite to the rotational direction of the grinding brush 12. The grinding brush 12 is pressed to the coating 32 by a brush pressing means 22 so as to grind the steel pipe. It is desirable that a high-density twist brush formed by closely implanting wires on the outer peripheral surface of a disc is used as this grinding brush 12.