Abstract: A first translation stage which holds an optical fiber and a second translation stage which holds a laser diode package are provided, and these translation stages are movable in the X-, Y- and Z-axis directions. A third translation stage movable in the X-, Y- and Z-axis directions is provided, on which are mounted a microscopic video camera and a laser head. On a video monitor a cursor is moved to the positions of the fiber tip and a laser diode in the laser diode package displayed on the monitor screen and the coordinates of the fiber tip and the laser diode are determined, on the basis of which the fiber tip and the laser diode are moved toward each other. The laser diode is excited and the fiber tip and the laser diode are positioned relative to each other so that the power of laser light received at the fiber tip becomes maximum. Then the laser light is applied from the laser head to the position where to fix the optical fiber, thereby welding or soldering it to the laser diode package.