An optical waveguide device includes: a channel waveguide which is positioned at a predetermined height relative to a bottom surface of a substrate; and a slab waveguide having a cross-sectional shape wider than that of the channel waveguide, being positioned at a predetermined height relative to the channel waveguide. Initially, an input end face of the optical waveguide device is vertically scanned with a light beam to achieve optical coupling with the slab waveguide, followed by transversely scanning to achieve optical coupling with the channel waveguide, hence, alignment of an optical axis with a minute channel waveguide can be effected easily and quickly.