To provide an assembling pin for aluminum fittings to facilitate assembling, to enhance work efficiency, and to guarantee smooth operation after assembling.

This assembling pin is so-structured with an insertion introducing part 6r being provided at its tip, an expanded outer diameter part 6a, 6b are subsequently provided by forming an axial projecting bar by a knurling process, and a head part 6h is provided at its rear end. It is also so structured, that if necessary, subsequently to the insertion leading part 6r, the expanded outer diameter parts 6a, 6b are provided one by one at the front and back of a straight part 6s, so as to sandwich the straight part, and the length of the insertion leading part 6r gets longer than the length from the front of the expanded part 6a to the joint of the head part 6h. This assembling pin 6 for aluminum fittings is applied for assembling the fins of a louver.