In the enlarged image smoothing method and device, an original enlarged image obtained by enlarging an original image m times (m is an integral number which satisfies the condition that m.gtoreq.2) in main and sub scanning directions is input, a first image is generated by moving the original enlarged image in a first direction, a second image is generated by moving the original enlarged image in a second direction opposite to the first direction, an AND operation is performed between the first image and second image, and an OR operation is performed between an image resulting from the AND operation and the original enlarged image, whereby the original enlarged image is smoothed.