The present invention is directed to an element for modulating area, in which there is used a functional molecular element adapted to change, by application of electric field, conformation of disc-shape like organic metallic complex molecule to exhibit function so that the structure of the organic metallic complex molecule is changed by application of electric field and the occupation area thereof is thus changed. The area modulating element is adapted to variously change molecular structure in accordance with control of applied electric field to change occupation area of molecule to thereby constitute a functional device such as optical filter and/or optical screen, etc.