The invention discloses a lightening case. The structure of the weight reducing case comprises a pull bar, a lightening device, a shell, casters, a small storage chamber, a zipper and a handle, the pull bar is arranged at the top of the shell, the pull bar goes through the shell and is in sliding fit with the shell, the quantity of the casters is four, the four casters are respectively mounted atthe bottoms of four corners of the shell, the lightening device is mounted in the shell, the small storage chamber is arranged on the front panel of the shell, the small storage chamber and the shellare arranged to for an integral structure, the zipper encircles around the shell, the zipper is in chain connection with the shell, the handle is arranged at the top of the shell, and the handle is fixedly mounted on the top panel of the shell. The coaction of a power device, the movable lightening device and a lightening device folding and unfolding mechanism makes the lightening of the case in the use process realized; and the lightening device is simple to fold and unfold, so the lightening case is convenient to use.