Polysilane polymers bearing hydroxyalkyl or alkoxyalkyl groups form monolayers (L films) at an air-water interface. It is possible to transfer all of the L films to hydrophobic substituents to provide Langmuir-Blodgett films. Among these polymers, polysilanes having more than three alkyl carbons have provided oriented polysilane thin films in which the silicon main chains align with each other in the direction parallel to the dipping direction of the substrates. The orientations were evaluated by their polarized UV absorptions. The dichroic ratios increase when Ca2+ ions were added to the water. Polysilane films with alkoxyalkyl groups show abrupt thermochromic transitions, while polysilanes with hydroxyalkyl groups show no thermochromism.