The invention relates to a silica optical waveguide having a clad layer and a core formed from a silica material and a method of fabricating the same and provides a silica optical waveguide in which the position of a core can be easily recognized and a method of manufacturing the same. The waveguide has a lower clad layer formed from silicate glass on a silica substrate, a core formed from silicate glass on the lower clad layer, and an upper clad layer formed of silicate glass on the lower clad layer so as to embed the core. A difference of height is provided on a top surface of the upper clad layer such that a difference between reflections from the position of the core and from other positions can be recognized on the top surface of the upper clad layer.