Method for producing polyphenylene ether

Method for producing polyphenylene ether, comprising preparing a polymerization solution of 10-25 parts by mass of a phenolic compound (M) and 75-90 parts by mass of an aromatic solvent (A) with the total of the compound and the solvent being 100 parts by mass, and 0.1-10 parts by mass of a catalyst (C) containing a metal salt; performing oxidative polymerization of the phenolic compound (M) by passing oxygen-containing gas through polymerization solution; stopping polymerization by mixing aqueous chelating agent solution into polymerization solution; subjecting a diphenoquinone compound produced as a by-product to quinone binding process or removal by reduction; and obtaining polyphenylene ether by separating aqueous phase through liquid-liquid separation. In the method for producing a polyphenylene ether, 0.001-0.004 part by weight of an ion catalyst (D) is added into the polymerization solution before the liquid-liquid separation.