A first lens transmits a beam of light having a vertical cross-sectional diameter made closer to a horizontal cross-sectional diameter. The beam of light is emitted from an optical waveguide on a substrate and configured such that the vertical cross-sectional diameter which is the diameter of a vertical cross section along the direction of the thickness of the substrate is greater than the horizontal cross-sectional diameter which is the diameter of a horizontal cross section along the direction of the width of the substrate. A second lens is disposed at a position, at which the vertical cross-sectional diameter and the horizontal cross-sectional diameter coincide with each other, so as to focus the beam of light on the optical fiber. The position is closer to the optical fiber than the first lens along the direction of travel of the beam of light transmitted by the first lens.