Provided is a method of fabricating a ridge type waveguide integrated semiconductor optical device. The method includes: separating a substrate into an active waveguide region and a passive waveguide region and selectively epitaxial-growing an active layer and a passive layer in the active waveguide region and the passive waveguide region, respectively, such that the active layer and the passive layer are vertically aligned with each other; sequentially forming a capping layer and an electrode connection layer on the active layer and the passive layer; forming a first insulating layer pattern on a predetermined region of the electrode connection layer disposed in the active waveguide region and simultaneously, forming a second insulating layer pattern on a predetermined region of the electrode connection layer disposed in the passive waveguide region; forming a shallow ridge type active waveguide and a shallow ridge type passive waveguide by performing an etching process using the first and second insulating layer patterns as etch masks until the capping layer is etched to a predetermined depth; and forming a passivation pattern on the entire surface of the shallow ridge type active waveguide and forming a deep ridge type passive waveguide by performing an etching process using the second insulating layer pattern as an etch mask until the substrate is etched to a predetermined depth.