A liquid extract production system, comprising: a processing liquid tank for storing a processing liquid; an extractor for extracting a liquid extract from extraction raw materials; a liquid extract tank for storing the liquid extract; a first flow path of the processing liquid that connects the processing liquid tank and the extractor ; a second flow path of the liquid extract that connects the extractor and the liquid extract tank ; a flow meter positioned in the second flow path for measuring the flow rate of the liquid extract in the second flow path ; a density meter positioned in the second flow path for measuring the solid content concentration of the liquid extract in the second flow path , wherein the density meter measures the refractive index of the liquid extract, and wherein the density meter calculates the Brix of the liquid extract based on the measured refractive index; a solid content calculation unit for calculating the solid content included in the liquid extract that flowed through the second flow path based on the measured flow rate and solid content concentration; a liquid transfer controller for controlling the transfer of the processing liquid from the processing liquid tank to the extractor and the transfer of the liquid extract from the extractor to the liquid extract tank based on the calculated solid content; a first liquid transfer pump controlled by the liquid transfer controller to stop the transfer of the processing liquid from the processing liquid tank to the extractor when the calculated solid content becomes a first reference value; and a second liquid transfer pump controlled by the liquid transfer controller to stop the transfer of the liquid extract from the extractor to the liquid extract tank when the calculated solid content becomes a second reference value that is greater than the first reference value. a processing liquid tank for storing a processing liquid; an extractor for extracting a liquid extract from extraction raw materials; a liquid extract tank for storing the liquid extract; a first flow path of the processing liquid that connects the processing liquid tank and the extractor ; a second flow path of the liquid extract that connects the extractor and the liquid extract tank ; a flow meter positioned in the second flow path for measuring the flow rate of the liquid extract in the second flow path ; a density meter positioned in the second flow path for measuring the solid content concentration of the liquid extract in the second flow path , wherein the density meter measures the refractive index of the liquid extract, and wherein the density meter calculates the Brix of the liquid extract based on the measured refractive index; a solid content calculation unit for calculating the solid content included in the liquid extract that flowed through the second flow path based on the measured flow rate and solid content concentration; a liquid transfer controller for controlling the transfer of the processing liquid from the processing liquid tank to the extractor and the transfer of the liquid extract from the extractor to the liquid extract tank based on the calculated solid content; a first liquid transfer pump controlled by the liquid transfer controller to stop the transfer of the processing liquid from the processing liquid tank to the extractor when the calculated solid content becomes a first reference value; and a second liquid transfer pump controlled by the liquid transfer controller to stop the transfer of the liquid extract from the extractor to the liquid extract tank when the calculated solid content becomes a second reference value that is greater than the first reference value. <EOS>