In an embodiment, a writing device receives a binary signal in accordance with image data, and writes an image based on the signal. The writing device includes a multiple-value unit (300) and a writing unit (500). The multiple-value unit (300) outputs a multiple-value signal based on the received binary signal. The number of the multiple values is an integral multiple of the binary. The writing unit (500) writes a binary image having a lager resolution than the image data based on the multiple-value signal.