An image forming device includes a plurality of image formation units each configured to form an image of one of a plurality of colors, and a patch image transfer unit configured to control transfer conditions during transferring a patch group that is a pattern for detecting a position shift and formed on an intermediate transfer belt onto a secondary transfer belt. The patch image transfer unit is configured to transfer patches of at least single color for which a band of transfer efficiency is narrowest, of the patch group, onto the secondary transfer belt under transfer conditions for the color, and during transition to the transfer conditions for the color from other transfer conditions or during transition from the transfer conditions for the color to the other transfer conditions, patches of a color other than the color, of the patch group is transferred onto the secondary transfer belt.