A method for producing a branched-polyether resin composition of the present invention includes a first step of obtaining a reaction mixture including: (1-A) a branched-polyether resin (X) containing a hydroxyl group, an acryloyl group, and an epoxy group and (1-B) at least one resin component selected from the group consisting of (1-B-1) a diacrylate (A2) of an aromatic difunctional epoxy resin, (1-B-2) a monoacrylate (A1) of an aromatic difunctional epoxy resin, and (1-B-3) an aromatic difunctional epoxy resin (B) other than (A1) and (A2); and a second step of mixing the reaction mixture and an unsaturated monocarboxylic acid, and reacting the epoxy group in the reaction mixture and a carboxyl group in the unsaturated monocarboxylic acid.