Etching treatment control device using phosphoric acid aqueous solution

The present invention provides an etching treatment control device using an aqueous phosphoric acid solution. The etching treatment control device includes a processing tank for etching a substrate byan etching liquid obtained by heating an aqueous phosphoric acid solution, a processing liquid supply unit that supplies a phosphoric acid aqueous solution to the processing tank; a processing liquidcirculation unit that causes an etching liquid circulation inside the processing tank; a processing liquid discharge unit that discharges the etching liquid; a concentration sensor that measures a silicon concentration in the etching liquid; and a control unit that is connected to the concentration sensor. The processing liquid supply unit, the processing liquid circulation unit, and the processing liquid discharge unit are controlled, wherein the control unit circulates the etching liquid by the processing liquid circulation unit, and measures the silicon concentration at a predetermined timing through the concentrat