We have developed an image eraser for reuse of paper printed on with decolorizable toner, which is composed of leuco dye and developer. The decolorizable toner loses color when heated. The image eraser enables decolorization of a bundle of paper instead of one sheet at a time. Before designing the image eraser, we studied three problems caused by heating, ghost images, sticking, and color change of paper. We have optimized the heating conditions of the image eraser, i.e., the heating temperature is 130–140 °C, and the heating period is 2h.