To provide a preventing device of sliding-down of the shoulder strap by using a hook part of a shoulder strap with a bag main body or a handle thereof.

The hook part 70 is provided at either the bag main body 20 or a portion between the opposite end parts of the shoulder strap 40 which are fitted to the bag main body 20. At either the bag main body or the portion between the opposite end parts of the shoulder strap 40 where the hook part is not provided, an engaging part 80 for engaging the portion between the opposite end parts of the shoulder strap 40 with the bag main body 20 by hooking the hook part 70 thereon removably, is provided.