A waste material supply device includes a hopper into which a waste material is supplied, a first rubbish supply apparatus having an inlet connected to an outlet of the hopper and a pusher configured to push out the waste material in a horizontal direction, a connecting chute having an upper portion connected to an outlet of the first rubbish supply apparatus to form a space extending upward and downward, and a second rubbish supply apparatus having an inlet connected to a lower portion of the connecting chute and a screw configured to convey the waste material in an axial direction according to rotation about an axis thereof, wherein the first rubbish supply apparatus has a plurality of pushers in a widthwise direction, and each of the pushers is able to be individually manipulated.