A memory device of the present invention is characterized by a memory device for storing information by making use of molecular alignment of a liquid crystal compound in a liquid crystalline state formed by spot irradiation with a laser beam to carry out a selective heat treatment on an electroconductive liquid crystal semiconductor material layer containing a liquid crystal compound, comprising: a first electrode group including a plurality of linear electrodes which are parallel to each other; an electroconductive liquid crystal semiconductor material layer formed in such a manner that the layer covers the first electrode group, the layer containing a liquid crystal compound having a long linear conjugate structural moiety and exhibiting a smectic phase as a liquid crystal phase; and a second electrode group formed on the electroconductive liquid crystal semiconductor material layer and including a plurality of linear transparent electrodes being parallel to each other and extend in a direction intersecting with the first electrode group.