To solve a problem of an existing leather backpack that it cannot be used in other fashions than as a backpack and cannot be used as a shoulder bag with a shoulder strap hanging from the shoulder to the waist because only two backpacking shoulder straps are attached, so that it has less value as a commodity.

This leather backpack has detachable shoulder strap attaching parts on both right and left sides 2 of the backpack main body 1. In another case, the backpack may have such attaching parts 3 that are passed under hanging straps 8 attached on both right/left sides 2 of the backpack main body 1 and are detachably attached to lower belts 9a of the backpacking shoulder straps 9 raised along the right/left sides 2.