To surely manufacture a largely acute radius-coping at a low cost without an excessive equipment by separately forming a top wall and both side walls, welding them at engagement parts, and assembling them.

A top wall 1 and both side walls 2, 2 of a coping to be covered over a parapet are separately formed. In the top wall, an aluminum sheet is cut to the prescribed arc shape with radius, and bent in the width direction according to each end inclined type or a single inclined type of the coping to form inclined parts 7, 7, in the side walls 2, 2, the prescribed radius is worked to an extruded member in which engagement parts 11, 11 to receive an edge of the top wall 1 are formed on the upper end. The top wall 1 is assembled with the side walls 2 by the welding at the engagement part. The largely acute radius coping can surely be manufactured at a low cost without any excessive equipment.