The invention provides an electro-optic hybrid circuit board having an optical waveguide superposed on a wiring circuit board, the electro-optic hybrid circuit board comprising: an insulating layer; a conductor pattern formed on the insulating layer; an undercladding layer formed on the conductor pattern-having insulating layer so as to surround the conductor pattern; a core layer formed on the undercladding layer; and an overcladding layer formed to cover the core layer and the undercladding layer.