An image forming apparatus for forming images at a plurality of resolution levels including at least one low resolution level and one high resolution level includes a photoconductor, onto which a beam size is set for the low resolution level; and an adjustment unit to conduct an exposure time-based density adjustment using a plurality of half-tone patterns prepared by changing an exposure time per pixel at a timing when a resolution level shifts from the low resolution level to the high resolution level and before actually shifting to an image forming operation executed at the high resolution level.