To make an attaching clamp for a backpack durable for a long time by using a connecting plate made of a metal element (metal plate).

This attaching clamp has a shoulder strap attaching ring 3 and a connecting plate 4. The connecting plate 4 is a metal plate with through holes 4b formed at both ends, which is double-folded so that the through holes 4b at both ends are overlapped. And recesses 4c are formed on both sides at one end and patches 4a on both sides at the other end of the metal plate. A calking member 8 is inserted into the through holes 4b to fasten the double- folded metal plate so that the double-folded metal plate will not be opened. A metal support cylinder 9 for supporting the shoulder strap attaching ring 3 is held at the folding part 4d of the double-folded metal plate, and both ends of the support cylinder 9 are turned back and closely fixed to both ends of the folding part 4d respectively. And the patches 4a are turned up and fixed to the recesses 4c of the metal plate respectively.