A method of manufacturing an opto-electric hybrid board which is capable of reducing the number of steps for the manufacture of the opto-electric hybrid board and which achieves the reduction in thickness of the opto-electric hybrid board to be manufactured, and an opto-electric hybrid board obtained thereby. A resist layer is formed on a core-forming resin layer, and is then formed into a predetermined pattern. Resultant portions of the core-forming resin layer serve as cores (optical interconnect lines) 3. Next, a thin metal film 5 is formed on the under cladding layer 2 so as to cover the resist layer and the cores 3. Thereafter, the resist layer is removed together with portions of the thin metal film 5 lying on the surface of the resist layer. Electroplating is performed on the remaining portions of the thin metal film 5 to fill grooves 6 defined between adjacent ones of the cores 3 with electroplated layers 7a obtained by the electroplating. The electroplated layers 7a serve as electrical interconnect lines 7.