An image forming apparatus includes an image bearer, an image forming device to form a toner image on the image bearer, a transfer device to transfer the toner image to a recording medium, a line sensor as an image density sensor to detect image density of the toner image, and a controller operatively connected to the image density sensor. The image density sensor is disposed so as to be shorter in a rotational direction of the image bearer than in a width direction of the image bearer perpendicular to the rotational direction of the image bearer. The controller forms a shading pattern image including a plurality of patches on the image bearer, and detects image density of the plurality of patches, so as to control image density. The shading pattern image is shorter in the rotational direction of the image bearer than in the width direction of the image bearer.