To provide an apparatus for measuring eccentricity, capable of obtaining a superior spot image even when a measuring object surface is aspheric, and capable of performing accurate measurement of eccentricity.

The apparatus 1 for measuring the eccentricity includes an illuminating optical system 10 which radiates illuminating light to the measuring object surface 5, a condensing optical system 20 which condenses reflection reflected on the measuring object surface 5 on a light condensing surface 31, an optical position sensor 30 which detects the position of spot light on the light condensing surface 31, and an arithmetic processing unit 35 which measures the amount of eccentricity of the measuring object surface 5 on the basis of the position of the spot light. The condensing optical system 20 is constituted by having a concave cylindrical lens 21 which diffuses the reflection in prescribed directions, a convex cylindrical lens 22 which equals the concave cylindrical lens 21 in an absolute value of refractive power and makes the reflection converge in a prescribed direction, a condenser lens 23 which condenses the reflection on the condensing surface 31, and a rotary driving device 25 which can compensate the effect of astigmatism brought about according to the measuring object surface 5, by relatively rotating the concave cylindrical lens 21 and the convex cylindrical lens 22 around the optical axis.