An image reading device includes a first setting processing portion, a second setting processing portion, and a third setting processing portion. The first setting processing portion, when first reference data has been read in a first reading process in which image data is read from a sheet placed on a sheet placement portion, sets a first adjustment value which is used in a shading correction. The second setting processing portion, when second reference data has been read in a second reading process in which image data is read from a sheet conveyed by a sheet conveying portion, sets a second adjustment value which is used in the shading correction. The third setting processing portion, in a case where only one of the first adjustment value and the second adjustment value has been set, sets the other based on the one that has been set.