Provided is an image processing device by which graininess of a target image is eliminated while outlines in the target image are maintained. The image processing device includes a smoothing unit and a weighted averaging unit. The smoothing unit is configured to generate a smooth image by smoothing the target image. The weighted averaging unit is configured to generate a weighted average image by performing weighted averaging of the target image and a difference image. The difference image is an image that is obtained by subtracting the target image from the smooth image.