An optical instrument comprising an eye refractive power measurement index optical system (50) for projecting an eye refractive power index in order to measure the refractive power of an eye (E) to be examined, a fixed index projecting optical system (10) for fixing/fogging the eye (E), an observation optical system (40) for observing the eye (E), a light receiving optical system (60), a ring plate (30) and an infrared LED (34) for projecting a cornea shape index used to measure the cornea shape of the eye (E), a ring plate (80) and an infrared LED (84) for projecting light to the center of the cornea via an objective lens (22), and an alignment index projecting optical system (70), whereby it is possible to project part of the cornea shape index onto the cornea (Ec) of the eye to be examined via the objective lens (22) of the observation optical system (40) for observation.