To realize easy and reliable temporary stopping of a component member regardless of some dimensional error at a fitting part by a structure wherein the end part of a casing is pressed and fixed by means of a plurality of inward protrusions formed at a specified interval by pressing the end face at the tubular part of a header fitted over the end part of the easing.

Header 11 of an EGR cooler is provided, on one end side thereof, with a tubular part 11A being stopped temporarily to the outside at the end part of a tubular easing 12. At first, the tubular part 11A of the header 11 is fitted over the end part of the casing 12. Subsequently, the tubular part 11A is provided, in the end face thereof, with recesses 13 at a specified interval by applying a pressure by means of a punch P thus forming a plurality of inward protrusions 14A, 14B through shift of the recesses 13 in the central direction. The plurality of protrusions 14A, 14B press the end part of the casing 12 strongly in the central direction thus stopping the header 11 temporarily to the end part of the casing 12.