To provide a bumper attaching structure wherein a rear bumper attaching part and a car body side attaching part are easily aligned when a rear bumper is attached.

A protruded piece 8 provided in a rear bumper is integrally formed in the backside of a rear bumper 2, and protruded toward the front of a car body. The protruded piece 8 has a flat plate-like substrate 23, the substrate 23 has a lower attaching hole part 10 formed in its tip side to insert a clip for attaching, and a drain oblong hole 24 is formed in its center part. In both sides of the substrate 23, reinforcing flanges 25 and 26 are erected, an extended part 27 of tongue piece-form is inclined from the substrate 23 such that its tip part is downward, its width is narrower than that of the substrate 23, and a plate thickness is thinner than the substrate 23 to provide flexibility.