PURPOSE: To improve the efficiency of adjusting operation for positioning the photodetecting end surface of a photoconductor cable at the focal point of a lens by moving and adjusting the photoconductor cable in the axial direction of the hole of a pedestal through gears, and automating the adjustment.

CONSTITUTION: Gears 31a and 31b engaging with bolt shafts 10a and 10b threadably are rotated to move the pedestal 16 as shown by an arrow A, and gears 32a and 32b engaging bolt shafts 13d and 13b threadedly are rotated to move the pedestal 16 as shown by an arrow B, positioning the photodetecting end surface of the photoconductive cable 5 at the focus axis of the lens 2. A gear 33 is rotated to move the photodetecting end surface of the cable 5 as shown by an arrow C, positioning the photodetecting end surface of the cable 5 at the focal point of the lens 2. Then, the gears are rotated forward and backward by a motor attached to the pedestal 16 to automate the adjustment. Consequently, the efficiency of the adjusting operation is improved.