An evaporator for use in a turbo refrigerating machine comprising: a shell forming the external appearance of the evaporator; a gas-liquid separator unit formed within the shell, separating gaseous refrigerant and liquid refrigerant from a refrigerant mixture introduced through a refrigerant inlet; a distributor unit (200, 300, 400, 500, 600) formed under the gas-liquid separator unit and provided with a plurality of refrigerant dropping units (250, 330, 460, 530, 650) formed at the lower portion thereof so as to uniformly distribute the liquid refrigerant introduced from the gas-liquid separator unit; and a heat transfer pipe provided under the distributor unit (200, 300, 400, 500, 600) for heat exchange between the liquid refrigerant distributed by the distributor unit (200, 300, 400, 500, 600) and chilled water in the heat transfer pipe, wherein the gas-liquid separator unit includes: a housing in which the length in a lengthwise direction is longer than the length in a widthwise direction, a gaseous refrigerant outlet through which the separated gaseous refrigerant is discharged from the gas-liquid separator unit to the outside of the housing, and a liquid refrigerant outlet through which the separated liquid refrigerant is discharged from the gas-liquid separator unit to the distributor unit (200, 300, 400, 500, 600); the liquid refrigerant outlet includes a plurality of through holes formed through a lower surface of the housing; and an eliminator provided above the gaseous refrigerant outlet, characterized in that the gas-liquid separator unit further includes a plurality of porous plates, provided within the housing, separating gaseous refrigerant and liquid refrigerant from a refrigerant mixture introduced through the refrigerant inlet, the gaseous refrigerant outlet is located at one end of the housing opposite the refrigerant inlet 110 located at the other end of the housing 120 in the lengthwise direction, the plurality of porous plates is separated from each other by a predetermined interval in the lengthwise direction of the housing. a shell forming the external appearance of the evaporator; a gas-liquid separator unit formed within the shell, separating gaseous refrigerant and liquid refrigerant from a refrigerant mixture introduced through a refrigerant inlet; a distributor unit (200, 300, 400, 500, 600) formed under the gas-liquid separator unit and provided with a plurality of refrigerant dropping units (250, 330, 460, 530, 650) formed at the lower portion thereof so as to uniformly distribute the liquid refrigerant introduced from the gas-liquid separator unit; and a heat transfer pipe provided under the distributor unit (200, 300, 400, 500, 600) for heat exchange between the liquid refrigerant distributed by the distributor unit (200, 300, 400, 500, 600) and chilled water in the heat transfer pipe, wherein the gas-liquid separator unit includes: a housing in which the length in a lengthwise direction is longer than the length in a widthwise direction, a gaseous refrigerant outlet through which the separated gaseous refrigerant is discharged from the gas-liquid separator unit to the outside of the housing, and a liquid refrigerant outlet through which the separated liquid refrigerant is discharged from the gas-liquid separator unit to the distributor unit (200, 300, 400, 500, 600); the liquid refrigerant outlet includes a plurality of through holes formed through a lower surface of the housing; and an eliminator provided above the gaseous refrigerant outlet, characterized in that the gas-liquid separator unit further includes a plurality of porous plates, provided within the housing, separating gaseous refrigerant and liquid refrigerant from a refrigerant mixture introduced through the refrigerant inlet, the gaseous refrigerant outlet is located at one end of the housing opposite the refrigerant inlet 110 located at the other end of the housing 120 in the lengthwise direction, the plurality of porous plates is separated from each other by a predetermined interval in the lengthwise direction of the housing. a housing in which the length in a lengthwise direction is longer than the length in a widthwise direction, a gaseous refrigerant outlet through which the separated gaseous refrigerant is discharged from the gas-liquid separator unit to the outside of the housing, and a liquid refrigerant outlet through which the separated liquid refrigerant is discharged from the gas-liquid separator unit to the distributor unit (200, 300, 400, 500, 600); the liquid refrigerant outlet includes a plurality of through holes formed through a lower surface of the housing; and an eliminator provided above the gaseous refrigerant outlet, characterized in that the gas-liquid separator unit further includes a plurality of porous plates, provided within the housing, separating gaseous refrigerant and liquid refrigerant from a refrigerant mixture introduced through the refrigerant inlet, the gaseous refrigerant outlet is located at one end of the housing opposite the refrigerant inlet 110 located at the other end of the housing 120 in the lengthwise direction, the plurality of porous plates is separated from each other by a predetermined interval in the lengthwise direction of the housing.