To enable a user to take out a thing from a bag, from a small shoulder bag to a large golf bag, with vacant both hands at need without putting the bag on a floor or a shelf by equipping a side belt on the bag to prevent a shoulder belt of the shoulder bag from slipping off the shoulder without tiring the user even if the bag is hung on a shoulder for a long time.

An additional side belt 4 detachable to all bags, including a shoulder bag, music instrument case, pochette, note personal computer case, sport bag, etc., is attached to this bag with shoulder belt. Thus a user can take out a thing from the bag at need with both vacant hands.