PURPOSE: To form an irregular groove over entire length and a peripheral groove for increasing bonding strength with resin via the application of cold molding and machining to the surface of a bush.

CONSTITUTION: The external surface of a bush 4 is pressed all around with a jig shorter than the length thereof, thereby forming an irregular groove. Peripheral and axial bonding strength between a molded resin material 3 and the bush 4 is increased, due to a stepped section 5c between the irregular groove and an axial un-machined section. As a result, an inexpensive un-machined tube can be used, and a material can be saved at a cold molding process. Also, a cold molding machine and a machining facility can be eliminated, requiring only a simple pressing machine. Also, a manufacturing process can be shortened, because of the elimination of a machining process.