A writing device is provided for color electronic paper which is capable of performing full color display. The writing device includes a head unit, a head unit moving mechanism which moves the head unit in a first direction, a feeding mechanism which moves electronic paper, and a controller. The head unit includes a writing head, an LED which emits light of three primary colors, an image sensing element consisting of a CMOS sensor, and an optical system. The writing head includes an optically transparent head main portion provided with pixel electrodes, and a common electrode (counter electrode). In the controller, an arrangement of three types of microcapsules in a microcapsule layer is detected to perform electric field formation for each of the pixel electrodes based on a detection result.