There is provided a method of producing a waveguide element comprising steps of forming a lower cladding layer having a refractive index n1 on a substrate having a lower electrode; forming an active core layer having a refractive index n2 and exhibiting an electro-optical effect on a surface of the lower cladding layer; forming a protective layer having a reflective index n4 on a surface of the active core layer; forming a passive core layer having a reflective index n3 on a surface of the protective layer; exposing the passive core layer with a predetermined pattern to form an optical circuit; forming an upper cladding layer on a surface of the passive core layer; forming an upper electrode on a surface of the upper cladding layer; and performing a polarization orientation treatment in which the active core layer is softened or liquidized and cured while the electric field is applied.