A reconstructed image with less noise is reconstructed from a lens array image. An image reconstructing device acquires the lens array image formed by a lens array comprising an array of multiple sub-lenses for an optical image of an object formed by a main lens. The image reconstructing device comprises an interpolation part interpolating a third sub-image formed by a third sub-lens based on the first sub-image and the second sub-image constituting the acquired lens array image, wherein the third sub-lens is positioned between the first sub-lens forming the first sub-image and the second sub-lens forming the second sub-image. The image reconstructing device comprises a reconstructing part reconstructing an image of the object formed by the main lens focused on a point at a given distance from the interpolated third sub-image, the first sub-image and the second sub-image.