PURPOSE: To easily position a face to be inspected by condensing diffracted light of calculator hologram for positioning the face onto a cross line of a plane including a rotation axis of a curved face to be inspected and the curved face.

CONSTITUTION: A glass substrate 2 is set so that a center 40 of calculator hologram 4 for positioning a face to be inspected of the substrate 2 aligns with an optical axis perpendicularly to an optical axis of an interferometer 100. Then light from a light source 9 is incident to a condensing lens 5, so that most part is transmitted and a part is reflected 5a to be a reference flux. The transmitted flux penetrates through the hologram 4, and diffracted light of a predetermined order emitted into a plane containing a rotation axis CC of a toric face 1a is condensed onto a cross line of the plane and the face 1a. The reflected light is transmission-diffracted 4 to generate interference fringes with the reference flux in a CCD camera 8. At this time if the rotation axis 12 of a subject table 11 aligns with the axis CC, no shift and inclination of a partial face 1bi to be inspected occurs. In numerous fringes occur with the axis shifted, the position and inclination of the object 1 can be adjusted 22 while observing the fringes to have the axes 12, CC easily aligned with each other.