An image processing device for identifying a characteristic of an eye from a face image comprising: a first differentiation unit configured to differentiate an eye region in at least a vertical direction of the eye to obtain a first luminance gradient; a first edge extraction unit configured to extract a first edge point according to the first luminance gradient; and a curve identification unit configured to identify a curve, which is a B-spline curve or a Bezier curve expressed by a control point and both end points and fits to the first edge point, as a curve expressing an upper-eyelid or lower-eyelid outline, the end points being an inner corner point of eye and a tail point of eye, by voting for the control point that is a voting target with respect to the first edge point using the Hough transform.