The EMV-200 electric field modulation spectrophotometer is capable of measuring changes in absorbance in the ultraviolet, visible and near-infrared region caused by application of an electrical field (several 100 V/µm) to film samples of optical performance materials. This system can perform quantitative measurement of changes in the dipole moment or polarizability and other characteristic sample parameters as a result of electronic excitation. This instrument is expected to extend the application to the evaluation of organic electro-luminescent (EL) materials, organic optical conversion molecules, and other molecular electronics elements. Furthermore, it will contribute to the elucidation of structures and functions related to optical excitation.