An image forming apparatus includes a transfer belt, a plurality of endless rotational bodies, an image forming device, a pattern sensor, and processing circuitry. The image forming device forms correction patterns including a first pattern as a straight line pattern orthogonal to a conveyance direction of the correction patterns and a second pattern as one of a straight line pattern orthogonal to and an oblique line pattern inclined with respect to the conveyance direction. The processing circuitry causes the image forming device to form the correction patterns using a correction value such that the second pattern included in one correction pattern on the transfer belt is same in color and shape as the second pattern included in at least one correction pattern of a preceding correction pattern and a following correction pattern in the conveyance direction with respect to the one correction pattern.