An reading device includes: a reading region setting section setting a reading region set under an inclination correction by an inclination correction section to be larger than a reading region set without the inclination correction, an image reading section reading a document in the reading region to generate image data, and a determination section defining a target region from a whole region of the image data and analyzing a portion of the image data corresponding to the document in the target region thereby determining an attribute of the image data, defining, without the inclination correction, a region obtained by inwardly narrowing the whole region of the image data by a predefined first region as the target region, and defining, under the inclination correction, a region obtained by inwardly narrowing the whole region of the image data by a second region larger than the first region as the target region.