1. An image forming apparatus comprising: an image carrier driven to rotate; a formation unit configured to form a first detection pattern for density detection on the image carrier for each color used in image formation; and a first sensor and a second sensor configured to detect the first detection pattern formed on the image carrier, the first detection pattern moving in a movement direction of a surface of the image carrier as the image carrier rotates, wherein the formation unit is further configured to form the first detection pattern on the image carrier such that a first detection pattern of an chromatic color is detected by the first sensor and a first detection pattern of an achromatic color is detected by the second sensor, and additionally form a second detection pattern for misregistration detection on the image carrier when forming the first detection pattern on the image carrier.