Abstract: A backpack has at least one air cushion and a backpack structure. At least one strap is mounted on the backpack structure and the air cushions are mounted onto the strap and backpack structure. The air cushion is mounted with a bladder having an air valve and an inflating device. A person uses the inflating device to add air into the bladder that is then capable of cushioning impacts by the bag and providing a perfect fit to the person. Accordingly, the backpack volume is minimized by pressing the air valve to discard the air and is convenient for storing.