A film forming apparatus that includes a mounting table for loading a wafer, a encompassing member surrounding the mounting table and dividing an inside of a process container, an exhaust part that vacuum exhausts the process container, a clamp ring loaded upon an upper space of the encompassing member and lifted from the upper space of the encompassing member while contacting an inner circumference part thereof with an outer circumference of the wafer loaded on the mounting table, and a cylindrical wall extended downward from the clamp ring, formed along a circumference of the clamp ring into a cylinder shape, and positioned between an outer circumference surface of the mounting table and an inner circumference surface of the encompassing member.