An image forming apparatus includes: a conveyor that transports a sheet; an image former that forms an image on front and back surfaces of the sheet being transported in a transportation path and forms marks on the front and back surfaces; a reader that comprises a first line sensor that is disposed on a front surface side and reads the front surface; and a second line sensor that is disposed on a back surface side and reads the back surface; and a controller that: calculates a positional deviation between the images formed on the front and back surfaces based on positions of the marks on the front surface read by the first line sensor and positions of the marks on the back surface read by the second line sensor, and controls the image former to adjust positions of the images formed on the front and back surfaces.