To provide a method for recovering a highly pure oxalic acid aqueous solution from an oxalic acid etching waste liquid left after the treatment of an indium-containing material to be etched.

This method for recovering the highly pure oxalic acid aqueous solution, comprising separating a dissolved metal component from an oxalic acid etching waste liquid left after the treatment of an indium-containing material to be etched, is characterized by bringing the oxalic acid etching waste liquid into contact with an anion exchange resin. By the recovering method, the highly pure oxalic acid aqueous solution can be recovered, and then recycled as an etching liquid. Thereby, the amount of the oxalic acid used in the etching treatment can be reduced. Consequently, a cost for making a transparent electrode can be reduced.

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