A number of holes (3) are formed in the outer circumferential wall (2) of a tubular metallic pipe (1) at regulator intervals in both circumferential and axial directions. Each of the holes (3) consists of a polygonal opening (4) and raised pieces (5) formed by bending the material from the peripheral edge surrounding the opening (3). This pipe may be used as an insert pipe in injection molding an article such as a lead screw, an optical fiber ferrule or the like. The raised pieces reinforce the part of the pipe surrounding each hole, and enhances the bonding between the molding material and insert pipe.