Transparent films of one-dimensional tetranuclear platinum complex, which has some mixed-valence states, was successfully prepared. Alumina gel and poly vinyl alcohol (PVA) were tested their suitabilities for a matrix. In the alumina matrix, their absorption spectra show that the Pt complex exists as the mixture with various valence states. On the contrast, in the PVA matrix, the absorption spectrum of the complex is unchanged from its solute sample state. THG properties were also investigated for their thin films.