An image forming device is provided, including a generation part, a determination part and a printing part. The generation part generates a plurality of types of binarized image data with respect to original image data. The determination part determines the binarized image data, in which an error between each of the plurality of the types of the binarized image data and the original image data is smaller, among the plurality of the types of the binarized image data. The printing part prints the binarized image data determined by the determination part on a medium.