An image forming apparatus includes a light beam scanner to scan an image bearer by a light beam according to data on a pattern for image positional deviation correction and a developing device to develop a latent image of the pattern. The pattern is formed on the image bearer by scanning performed by the light beam scanner. The image forming apparatus includes a transfer belt to transfer the pattern to a medium, a sensor to read the pattern to obtain an amount of image positional deviation, a skew correction device to adjust a tilt of an optical member of the light beam scanner according to a skew amount to correct a skew and perform the image positional deviation correction according to the amount of image positional deviation, and circuitry to drive the skew correction device before the image positional deviation correction.