There is provided an opto-electric hybrid board in which a metal reinforcement layer is in intimate contact with an insulative layer of a flexible circuit board without an adhesive layer interposed therebetween, the metal reinforcement layer allowing the proper mounting of an element while deformation due to pressing load applied during the mounting is suppressed. In the opto-electric hybrid board, a flexible double-sided circuit board in which electrical interconnect lines are formed on the front and back surfaces of an insulative layer having flexibility is used as an electric circuit board. A metal reinforcement layer is formed by plating on at least part of the electrical interconnect line on the back surface side which corresponds to a mounting pad on the front surface side. An optical waveguide is formed in contact with the electrical interconnect line on the back surface side of the flexible double-sided circuit board.