An image forming apparatus is disclosed. In at least one embodiment, the apparatus includes a plurality of image carriers to carry an image; a plurality of drivers to drive the image carriers; a plurality of drive-force transmitting members to transmit a driving-force from the drivers to image carriers; a developing unit, provided to the image carriers, to develop the image; a transfer member, facing the image carriers, to receive the image from the image carriers sequentially; an image detector to detect the image on the transfer member to check a detection timing of the image; a sensor, provided to each of the image carriers, to detect a rotational speed of image carriers; and a controller to conduct an image-to-image displacement control, a speed-deviation checking, and a phase adjustment control for each of the plurality of image carriers with the image detector and sensor.