An image forming apparatus for forming an image includes a first control table and a second control table. The first control table includes information on widths of a recording sheet, categorized into a plurality of groups of different widths thereof in a direction perpendicular to a sheet transport direction. The second control table includes information on timing of the recording sheet transported to the fixing device based on the group to which a preceding recording sheet, belongs and the group to which a subsequent recording sheet belongs. When a certain width of the recording sheet belongs to the plurality of the groups in the first control table, the group to which the preceding recording sheet belongs is the group to which the subsequent recording sheet belongs.