The device for treating food wastes comprises a housing which includes a feeding port formed at an upper side of the same for feeding food wastes, a drainage port formed at one side of a lower surface of the same for discharging leachate separated from the fed food wastes, and a discharge hole formed at the other side of the lower surface of the same for discharging dehydrated remnants among the food wastes; an inner casing which is installed at a certain distance from an inner wall of the housing and includes a drainage net installed at an upper side for discharging water fed together with the food wastes, a drum which is installed at a center of the same and has a plurality of wall surface blades at an inner circumferential surface, and a dehydration net installed at a lower side of the same for discharging leachate; a grinding screw which is vertically installed at an inner side of the inner casing and includes a plurality of screw blades installed at an outer circumferential portion and contacting with a wall surface blade of the drum, and the dehydration net.