Heat exchanger and production method of the heat exchanger

A heat exchanger comprising:

• a case having a side plate portion through which a first hole portion penetrates, a heating medium being supplied into the case;
• a heat transfer tube, an end portion of the heat transfer tube being inserted into the first hole portion;
• a header constituting member provided on an outer face side of the side plate portion, the header constituting member having a second hole portion into which the end portion of the heat transfer tube is inserted;
• and
• a first annular convex portion and a second annular convex portion that are provided for the heat transfer tube, outer diameters of the first and the second annular convex portions being partially expanded, the first and the second annular convex portions relatively fixing the side plate portion of the case, the heat transfer tube, and the header constituting member,
• wherein the first annular convex portion is positioned on an inner face side of the side plate portion and is engaged with a circumferential edge portion of the first hole portion, or the first annular convex portion is positioned in the first hole portion and contacts under pressure with an inner circumferential face of the first hole portion, and
• the second annular convex portion is positioned on an outer face side of the header constituting member and is engaged with a circumferential edge portion of the second hole portion.