Provided is an illuminator (103) including a light source that performs irradiation with light, a plurality of imaging units (202 and 203), position detectors (351 and 352) that detect a first position indicating a center of a pupil and a second position indicating a center of corneal reflection, from an image of an eye ball of a subject irradiated with light by the illuminator (103), and captured by the imaging units (202 and 203), and a calculator (353) that calculates a fourth position indicating a curvature center of a cornea, based on a position of the light source, a third position on a display, the first position, and the second position.
