An optical waveguide of the present invention is an optical waveguide having a first rib and a second rib being provided on a slab layer along one direction from one side to the other side and a barrier layer being connected between said first rib and said second rib, in which: the first rib includes a first taper part having a width widening from a first end in said one side to a second end connected with said barrier layer; and the second rib includes a first layer and a second layer laminated on a face of said slab layer in turn.