A color sorting machine, when conveying an object to be sorted along a conveyance route, the color sorting machine removing, in a sorting region, a predetermined object in the object to be sorted as foreign matter into a removal route extending from the sorting region, the color sorting machine comprising: a supply portion supplying the object to be sorted to the conveyance route; a sorting portion surrounding the sorting region, at least a part of the sorting portion being formed by a transparent wall; a first conveying portion surrounding the conveyance route from the supply portion to the sorting region and hermetically connected to the sorting portion; a second conveying portion surrounding the conveyance route from the sorting region and hermetically connected to the sorting portion; a removing portion surrounding the removal route and hermetically connected to the sorting portion; a detection device optically detecting the foreign matter in the object to be sorted conveyed through the transparent wall; a removal device ejecting air against the foreign matter in the sorting region so as to remove the detected foreign matter into the removal route; and an air intake port provided in the first conveying portion or the supply portion, wherein the sorting portion hermetically surrounds the sorting region except for the first conveying portion, the second conveying portion, and a portion communicating with the removing portion, and wherein the second conveying portion hermetically surrounds a periphery of the conveyance route from the sorting region to the first suction device, characterized in that the color sorting machine further comprises: a first suction device provided in the second conveying portion, wherein the first suction device sucks in air in the conveyance route, thereby generating an airflow heading for the second conveying portion from the air intake port via the sorting region. a supply portion supplying the object to be sorted to the conveyance route; a sorting portion surrounding the sorting region, at least a part of the sorting portion being formed by a transparent wall; a first conveying portion surrounding the conveyance route from the supply portion to the sorting region and hermetically connected to the sorting portion; a second conveying portion surrounding the conveyance route from the sorting region and hermetically connected to the sorting portion; a removing portion surrounding the removal route and hermetically connected to the sorting portion; a detection device optically detecting the foreign matter in the object to be sorted conveyed through the transparent wall; a removal device ejecting air against the foreign matter in the sorting region so as to remove the detected foreign matter into the removal route; and an air intake port provided in the first conveying portion or the supply portion, wherein the sorting portion hermetically surrounds the sorting region except for the first conveying portion, the second conveying portion, and a portion communicating with the removing portion, and wherein the second conveying portion hermetically surrounds a periphery of the conveyance route from the sorting region to the first suction device, characterized in that the color sorting machine further comprises: a first suction device provided in the second conveying portion, wherein the first suction device sucks in air in the conveyance route, thereby generating an airflow heading for the second conveying portion from the air intake port via the sorting region. a first suction device provided in the second conveying portion, wherein the first suction device sucks in air in the conveyance route, thereby generating an airflow heading for the second conveying portion from the air intake port via the sorting region.