Long-term measurement of noncentrosymmetric molecular orientation of vacuum-evaporated tris(8-hydroxyquinolinato) aluminum (III) (Alq(3)) thin film was performed by means of first-order electroabsorption (EA) spectroscopy. This molecular orientation is responsible for the giant surface potential of Alq(3) film, and it might be utilized to nonlinear optical devices. Although the EA response presented reduction, the relaxation time constant was on the order of year. Possible mechanisms for the reduction are discussed.