In an optical waveguide device of the present invention, optical element mount (17) includes first base block (19a) for supporting first optical element (18a) and second base block (19b) for supporting second optical element (18b) that has an active layer depth smaller than that of first optical element (18a). Second base block (19b) is formed from stacks of upper clad layers whose number of stacks is larger than that of first base block (19a). Difference (h1) in height between the first and second base blocks is equal to difference (d1−d2) in active layer depth between the first and second optical elements.