An image processing device comprising: an image data acquiring unit configured to acquire calibration image data obtained by an image capturing device comprising an aperture configured to adjust an amount of transmitted light, a lens array including a plurality of lenses, and an image sensing element configured to photo-electrically convert an image of a subject via the lens array; wherein the lens array is positioned between the aperture and the image sensing element, and wherein the image data acquiring unit is configured to acquire calibration image data comprising images of the subject via the lens array obtained with the aperture in a state where the aperture is stopped down in accordance with an instruction to calibrate the lens array and has a larger F-number than in a state where the aperture is fully opened; and a position acquiring unit configured to acquire, based on the calibration image data, positions of areas in the image sensing element where the images of the subject via the lens array included in the calibration image data are formed, wherein each of the images corresponds to one of the plurality of lenses; and a deviation calculating unit configured to calculate a deviation of the positions of the areas from expected positions of the areas based on the calibration image data, characterized in that the image processing device further comprises: an analyzing unit configured to obtain distances between a gravity center position of an area in the image sensing element where an image of the subject via one of the plurality of lenses is formed and positions of boundary pixels adjacent to boundary parts of the area, to perform an analysis based on an amount of fluctuation between the obtained distances using Formula below, div m n = std d m n θi, wherein div (m, n) is the amount of fluctuation, std () is a function for calculating the standard deviation, d () is the distance, (m, n) is a position of the lens and θi is a direction to search for the boundary pixels, and to decide that the calibration cannot be performed if a number or the lenses, whose amount of fluctuation exceeds a threshold, is above zero. an image data acquiring unit configured to acquire calibration image data obtained by an image capturing device comprising an aperture configured to adjust an amount of transmitted light, a lens array including a plurality of lenses, and an image sensing element configured to photo-electrically convert an image of a subject via the lens array; wherein the lens array is positioned between the aperture and the image sensing element, and wherein the image data acquiring unit is configured to acquire calibration image data comprising images of the subject via the lens array obtained with the aperture in a state where the aperture is stopped down in accordance with an instruction to calibrate the lens array and has a larger F-number than in a state where the aperture is fully opened; and a position acquiring unit configured to acquire, based on the calibration image data, positions of areas in the image sensing element where the images of the subject via the lens array included in the calibration image data are formed, wherein each of the images corresponds to one of the plurality of lenses; and a deviation calculating unit configured to calculate a deviation of the positions of the areas from expected positions of the areas based on the calibration image data, an analyzing unit configured to obtain distances between a gravity center position of an area in the image sensing element where an image of the subject via one of the plurality of lenses is formed and positions of boundary pixels adjacent to boundary parts of the area, to perform an analysis based on an amount of fluctuation between the obtained distances using Formula below, div m n = std d m n θi, wherein div (m, n) is the amount of fluctuation, std () is a function for calculating the standard deviation, d () is the distance, (m, n) is a position of the lens and θi is a direction to search for the boundary pixels, and to decide that the calibration cannot be performed if a number or the lenses, whose amount of fluctuation exceeds a threshold, is above zero.