The present invention provides a process for producing an electro-optic hybrid circuit board, which comprises the steps of: forming an undercladding layer on a metal foil side of a metal transfer sheet that comprises a releasable substrate and a metal foil formed thereon; forming a core layer on the undercladding layer; forming an overcladding layer so as to cover the core layer and the undercladding layer; stripping the releasable substrate from the metal foil; and etching the metal foil to thereby form a predetermined conductor pattern.