1. An image forming device, comprising: a sheet carrying body configured to carry a sheet thereon in a predetermined direction; a forming unit configured to form an image on one of the sheet carrying body and the sheet being carried on the sheet carrying body; and a control device configured to: select a pattern to be formed on the sheet carrying body from among a plurality of kinds of patterns depending on an image forming condition, 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; control the forming unit to form the selected pattern on the sheet carrying body; 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 perform positional deviation correction for the image to be formed on the sheet based upon the determined positional deviation.