To eliminate inconvenience, of conventional empty can treating devices, that metal scraps are required to be turned into fine fragments in order to dissolve metal again, when transporting them to dissolving plant, the transportation efficiency is bad and transportation cost is high by compressing the empty cans only, but the compression is better than the empty cans as they are.

After empty cans are pressed into flat plates in a compressing part 11, in a cutting part 12, they are cut into fine strips by an upper shredder. Next, the pieces are cut into fine fragments by a lower shredder having a pitch smaller than that of the upper shredder. Since the lower shredder has the smaller pitch than the upper shredder, fine strips formed by the upper shredder are surely cut by the lower shredder and turned into fragments. Moreover, in the compressing part 11, before pressing the empty cans into flat plates by a flat roll, they are deformed in irregular shapes in advance by a pair of rolls with projections to make them easily caught by the flat roll.