PURPOSE: To realize optical axis alignment only by moving a waveguide chip in a direction perpendicular to a groove part, by placing the waveguide chip at a prescribed position on a substrate, and forming the groove part in which the optical axis alignment can be realized only by arranging an optical fiber at the position on the substrate.

CONSTITUTION: The titled device includes the waveguide chip 1 on which an optical waveguide 3 is formed and the substrate 2 having a size possible to place the waveguide chip 1, and the groove parts 5AW5C are formed on the substrate 2. In other words, when the optical fibers 6AW6C are arranged at the position of a linear pattern including a line in which the optical waveguide 3 is extended to the substrate 2 side virtually in a center part at a state where the waveguide chip 1 is placed at a prescribed position on an optical waveguide forming plane, the groove parts 5AW5C with width in which the center part of the optical fibers 6AW6C coincides with the end face of the optical waveguide 3 are formed at the position of the linear pattern. In such a way, it is possible to move the waveguide chip in the direction perpendicular to the longitudinal direction of the groove part and to perform the optical axis alignment inevitably by placing the waveguide chip 1 on the substrate 2 and arranging the optical fibers 6AW6C in the groove parts 5AW5C.