To reduce the buckling of an attachment portion to assuredly provide desired reinforcing ability of a tubular portion, the attachment base 32 is raised to bring forward the contact surface 32f, forming the peripheral wall 38. This allows the impact beam 10 to be disposed in the vehicle so that the contact surface 32f closely contacts the mounting location 20 for the secure fastening of the impact beam 10 to the mounting location 20. The lateral edges of the attachment portion comprises the lateral flanges 40, 42 on the opposite sides of the peripheral wall 38, and the peripheral wall 38 and the lateral flanges 40, 42 together form the turnback portions 44, 46 on opposite sides of the attachment base 32, each turnback portions defining a concavity recessed from the contact surface 32f, and having a U-shaped section perpendicular to the centerline O of the tubular portion 12. This configuration provides an increased rigidity against external forces that have a component parallel to the length of the tubular portion 12 and reduce the buckling of the attachment portions 14, 16, thereby stably providing the desired reinforcing ability of the tubular portion 12.