In an image forming device, a correction unit corrects image formation operation based on a plurality of correction patterns. A pattern creation unit forms an electrostatic latent image of the correction patterns on a photoconductor and transferring the image to an intermediate transfer body to form the correction patterns thereon. A pattern detecting unit detects the correction patterns formed on the intermediate transfer body. A speed detecting unit detects a movement speed of the correction patterns on the intermediate transfer body are moved. A timing holding unit computes a set value of detection start timing for starting detection of each correction pattern to hold the set value. The correction unit is provided to determine, in advance of correcting image formation operation, a detection start timing based on the movement speed and the set value.