An optical sorting device comprising: a chute having an optical detection slit and a sorting and removal slit arranged on a downstream side of the optical detection slit, an object to be sorted flowing down on a front surface of the chute; an optical inspection unit having an illuminating part having a rear-side illuminating portion installed on a rear surface side of the chute and configured to emit light to the object to be sorted through an opening, a light receiving part configured to receive at least one of transmitted light and reflected light from the object to be sorted of the light emitted from the illuminating part, and an optical path configured to send at least one of the transmitted light and the reflected light to the light receiving part, the optical inspection unit being configured to inspect the object to be sorted flowing down on the front surface of the chute; and an ejector unit having an ejector nozzle capable of ejecting air to the object to be sorted flowing down on the front surface of the chute, and configured to sort and remove the object to be sorted based on an inspection result obtained by the optical inspection unit, the optical sorting device characterized by comprising: a base member attached to the rear surface side of the chute, wherein at least the rear-side illuminating portion and the ejector nozzle are attached to the base member, and the base member is installed such that the opening of the rear-side illuminating portion faces the optical detection slit, and a leading end of the ejector nozzle faces the sorting and removal slit, and wherein the base member or the rear-side illuminating portion includes a positioning protrusion to be inserted into the optical detection slit to position the base member on the chute. a chute having an optical detection slit and a sorting and removal slit arranged on a downstream side of the optical detection slit, an object to be sorted flowing down on a front surface of the chute; an optical inspection unit having an illuminating part having a rear-side illuminating portion installed on a rear surface side of the chute and configured to emit light to the object to be sorted through an opening, a light receiving part configured to receive at least one of transmitted light and reflected light from the object to be sorted of the light emitted from the illuminating part, and an optical path configured to send at least one of the transmitted light and the reflected light to the light receiving part, the optical inspection unit being configured to inspect the object to be sorted flowing down on the front surface of the chute; and an ejector unit having an ejector nozzle capable of ejecting air to the object to be sorted flowing down on the front surface of the chute, and configured to sort and remove the object to be sorted based on an inspection result obtained by the optical inspection unit, the optical sorting device characterized by comprising: a base member attached to the rear surface side of the chute, wherein at least the rear-side illuminating portion and the ejector nozzle are attached to the base member, and the base member is installed such that the opening of the rear-side illuminating portion faces the optical detection slit, and a leading end of the ejector nozzle faces the sorting and removal slit, and wherein the base member or the rear-side illuminating portion includes a positioning protrusion to be inserted into the optical detection slit to position the base member on the chute. a base member attached to the rear surface side of the chute, wherein at least the rear-side illuminating portion and the ejector nozzle are attached to the base member, and the base member is installed such that the opening of the rear-side illuminating portion faces the optical detection slit, and a leading end of the ejector nozzle faces the sorting and removal slit, and wherein the base member or the rear-side illuminating portion includes a positioning protrusion to be inserted into the optical detection slit to position the base member on the chute.