An image forming apparatus includes a conveyor, an image former, and a reading device. The conveyor conveys a medium in a conveyance direction. The image former forms an adjustment pattern on one side of the medium conveyed by the conveyor. The reading device downstream from the image former in the conveyance direction reads the adjustment pattern on the one side of the medium conveyed by the conveyor to generate read data. The adjustment pattern includes a first line segment and a second line segment that extend in directions different from each other and each are inclined with respect to the conveyance direction.