1. An image forming device, comprising: a sheet carrying body configured to carry a sheet thereon in a predetermined direction; a pattern selecting unit configured to select one of a plurality of kinds of patterns, the plurality kinds of patterns including a first pattern and a second pattern, the first pattern including a plurality of marks aligned at intervals of a predetermined distance within a first range, the second pattern including a plurality of marks aligned at intervals of a predetermined distance within a second range shorter than the first range; a forming unit configured to form the pattern selected by the pattern selecting unit on the sheet carrying body and to form an image on the sheet being carried on the sheet carrying body; a deviation determining unit configured to determine a positional deviation of the image to be formed on the sheet by the forming unit, based upon the pattern formed on the sheet carrying body by the forming unit; and a correcting unit configured to perform positional deviation correction for the image to be formed on the sheet based upon the positional deviation determined by the deviation determining unit.