Abstract: Binocular stereo microscope including an observation optical system to observe the patient's eye through binocular vision, comprising laser transmitting optical system for transmitting the therapeutic laser beam coaxially with the optical axis of an objective lens in the binocular stereo microscope to the patient's eye, alignment light beam projection optical system for projecting the alignment light beam onto the patient's eye to form an alignment index on the eye. CCD detects the index image projected on the patient's eye by the alignment light beam projection optical system, CPU judges alignment situation based on the image detected by the CCD, moving unit for moving the patient's eye relatively to the binocular stereo microscope is moved based on a judgement of the CPU.