An optical waveguide circuit component according to the present invention is characterized by that a clad layer composed of quartz is provided on the surfaces of a substrate and core formed by quartz doped selectively on a quartz plate structure, and a lid or a cover member is fixed onto the clad layer by heat pressing. With this structure, it is possible to reduce the magnitude of a polarization-dependent loss (PDL) generated when the lid and clad layer are combined.