A combination of a juice-extracting drum and a screw, said combination comprising: - screw; and - a juice-extracting drum that separates juice and debris of a juice-extracting target by said screw rotating inside, said juice-extracting drum comprising: an inner module formed as a hollow cylinder with an upper portion open to accommodate the screw; and an outer module having an upper portion open to be detachably coupled to the inner module, and formed with a rib formed by protruding in a radially interior direction on an interior circumference and including a protrusion surface, an upper surface, and a lower surface, characterized in that said inner module is formed with a plurality of slits formed as penetration holes having both lateral sides, an upper surface, and a lower surface along an interior circumference; wherein the rib of the outer module is inserted into the slit of the inner module when the outer module surrounds and combines the inner module and a fixed gap discharging juice extracted by the screw is formed lengthily in an up and down direction between the lateral side of the slit of the inner module and a lateral side of the rib of the outer module, wherein the fixed gap is formed in a direction intersecting a screw blade of said screw. - screw; and - a juice-extracting drum that separates juice and debris of a juice-extracting target by said screw rotating inside, said juice-extracting drum comprising: an inner module formed as a hollow cylinder with an upper portion open to accommodate the screw; and an outer module having an upper portion open to be detachably coupled to the inner module, and formed with a rib formed by protruding in a radially interior direction on an interior circumference and including a protrusion surface, an upper surface, and a lower surface, characterized in that said inner module is formed with a plurality of slits formed as penetration holes having both lateral sides, an upper surface, and a lower surface along an interior circumference; wherein the rib of the outer module is inserted into the slit of the inner module when the outer module surrounds and combines the inner module and a fixed gap discharging juice extracted by the screw is formed lengthily in an up and down direction between the lateral side of the slit of the inner module and a lateral side of the rib of the outer module, wherein the fixed gap is formed in a direction intersecting a screw blade of said screw. an inner module formed as a hollow cylinder with an upper portion open to accommodate the screw; and an outer module having an upper portion open to be detachably coupled to the inner module, and formed with a rib formed by protruding in a radially interior direction on an interior circumference and including a protrusion surface, an upper surface, and a lower surface, characterized in that said inner module is formed with a plurality of slits formed as penetration holes having both lateral sides, an upper surface, and a lower surface along an interior circumference; wherein the rib of the outer module is inserted into the slit of the inner module when the outer module surrounds and combines the inner module and a fixed gap discharging juice extracted by the screw is formed lengthily in an up and down direction between the lateral side of the slit of the inner module and a lateral side of the rib of the outer module, wherein the fixed gap is formed in a direction intersecting a screw blade of said screw.