An image forming apparatus includes an image bearer; a toner image forming device; a transfer rotator; a transfer device; a rotation position detector; an image density detector; a density data acquisition unit to causes the toner image forming device to form an adjustment toner image equal to or greater in length than a circumferential length of the image bearer, cause a linear velocity difference between the image bearer and the transfer rotator in transfer of the adjustment toner image, and acquires, from a detected image density of the toner image transferred from the image bearer, detected by the image density detector, image density unevenness data with reference to detection of a reference rotation position of one of the image bearer and a rotator; and a correction unit to adjust an image forming condition according to the reference rotation position, the image density unevenness data, and the linear velocity difference.