A virtual sensitivity value which is obtained, variously changing a pupil diameter is measured in advance for many examinees, and volume of correction which is necessary at the time when the sensitivity value is corrected into one in a standard pupil diameter is stored as correction volume database. An apparatus has measurement means for measuring the pupil diameter of the eye to be examined, computing means for computing a shape parameter rate of the measured pupil diameter to the standard pupil diameter, and judgment means for computing volume of correction by referring to the correction volume database from the shape parameter rate and correcting the virtual sensitivity value obtained by measurement of the eye to be examined and for judging a sensitivity step of the eye to be examined.