A glass capillary tube 1 is connected and fixed in a straight line to an optical component 5 having a substantially rectangular cross-section perpendicular to an optical axis 4a. Moreover, a top-surface side end portion 9 and a rear-surface side end portion 8 of an exterior surface 7 of the glass capillary tube 1 are positioned at the same level as the top surface and the rear surface of the exterior surface of the optical component 5 in the height-wise direction, respectively, while the central axis of an insertion hole 3, which is provided in the glass capillary tube 1 and into which an optical fiber 2 is inserted and fixed, is matched with the optical axis 4a of the optical component 5.