A photo-curing polysiloxane composition includes a polysiloxane, an o-naphthoquinonediazidesulfonate compound, and a solvent. The polysiloxane contains less than 30 wt % of a polysiloxane fraction having a molecular weight above 8,000, and 35 wt % to 60 wt % of a polysiloxane fraction having a molecular weight ranging from 500 to 2,000 when calculated from an integral molecular weight distribution curve obtained by plotting cumulative weight percentage versus molecular weight falling within a range between 500 and 50,000 measured by gel permeation chromatography. A protective film formed from the photo-curing polysiloxane composition and an element containing the protective film are also disclosed.