A film forming apparatus including a raw material supplying section for supplying a raw material of a liquid or a gas-liquid mixture, a raw material vaporizing section for vaporizing the raw material to form a raw material gas, and a film forming section for conducting a film forming treatment using the formed raw material gas, and a filter on the transport path for the raw material gas from the raw material vaporizing section to the film forming section. An outer edge of the filter is pressed to the inner surface of the transport path over the whole perimeter thereof by a cyclic supporting member, which is less prone to be deformed by a loading in the pressing direction than the outer edge, and is fixed to the inner surface of the transport path in a compressed state between the inner surface of the transport path and the supporting member.