To provide a back pad member improving the stability in walking and traveling of a user carrying a backpack by forming an upholstery material into a three-dimensional shape corresponding to the recessed/projecting shape of the back of the user, and to provide its manufacturing method.

This back pad member 4 for use in the backpack has a sheet-like upholstery coming into contact with the back of the user when carrying the backpack, and elastic core materials 21-24 disposed on the back side of the upholstery 1. The upholstery 1 used is formed into the three-dimensional shape corresponding to the recessed/projecting shape of the back of the user.