composite  plasterboard device of externally charging type, including a screen from the outside of which display and erasing operations can be repeatedly performed simply, and having an excellent memory retention performance of the recorded image and durability. Also, a hand-writable liquid crystal board set being excellent in operativity, performances, safety, including the above liquid crystal display device as a liquid crystal board. The liquid crystal display device includes a layered structure comprising, in the following order: a conductive layer; a transparent high-electric resistance layer having a volume resistivity of 10.sup.13 .OMEGA..cndot.cm or more in a 20.degree. C. air at a relative humidity of 90%; a liquid crystal-dispersed polymer layer which has a volume resistivity of 10.sup.13 .OMEGA..cndot.cm or more in a 20.degree. C. air at a relative humidity of 90%; and a transparent insulator layer. The hand-writable liquid crystal board set comprises: