PURPOSE: To reproduce tetraalkyammonium hydroxide to be used as the developer for a positive resist from a waste developer.

CONSTITUTION: The waste liq. of a developer for a positive resist consisting essentially of a tetraalkylammonium hydroxide is neutralized to remove the alkali-soluble org. matter dissolved in the waste liq. by precipitation and then electrolyzed in the anode compartment of an electrolytic cell divided with a cation-exchange membrane. In this case, the waste liq. is anodized in the anode compartment, the aq. tetraalkylammonium hydroxide soln. drawn off from a cathode compartment is further introduced into the anode compartment of another electrolytic cell and electrolyzed in multiple stages. Otherwise, the waste liq. is introduced into the anode compartment of an electrolytic cell divided into ≥3 compartments by ≥2 cation-exchange membranes and electrolyzed in multiple stages, the electrolyte in the intermediate compartment is circulated to an org. matter decomposing electrolytic cell and electrolyzed, and a tetraalkylammonium hydroxide recyclable as a developer is obtained from the cathode compartment of the final-stage electrolytic cell or from the cathode compartment of the multicomparment electrolytic cell.