PURPOSE: To make a corrosion protective covering adhesive with good accuracy and to perform a perfect corrosion protection, by forming a polyethylene covered end part in a slowly curved face and grinding it so that the start point of the curved face section becomes in a tangential shape to the steel pipe surface and the completion point to the covered surface respectively.

CONSTITUTION: The end part 3 of a polyethylene covering 2 is formed with a slowly curved face 5 like a sine curve, for instance, at its sectional shape in the axial direction and yet the start point (a) of a curved face section land the completion point (b) are made tangential for the surface of a steel pipe 1 and that of the polyethylene covering 2. A corrosion protective covering 4 is made adhesive to the curved face 5 with good accuracy by executing the corrosion protective covering 4 on the polyethylene covering 2 end part having the curved face 5 and no gap is caused at all between the both and steel pipe 1.