To prevent reflection of an illuminating light in the case of using a whiteboard or an electronic blackboard and to prevent an increase in a space by installing a plurality of types of information inputting media and projecting media.

The medium 11 for writing information to be written by a special purpose marker pen for erasing ink by supplying a water content 31 is provided by incorporating a matte surface via a protrusion and recess pattern. A writing sheet or screen for a projector of whiteboard or an electronic blackboard is used also by the same medium 11.