A film forming apparatus for forming a thin film on a flexible substrate. The film forming apparatus forms a thin film on a flexible substrate under vacuum. The film forming apparatus includes a first zone into which a first gas is introduced and a second zone into which a second gas is introduced in a vacuum chamber. Zone separators have openings through which the flexible substrate passes. The film forming apparatus includes a mechanism that reciprocates the flexible substrate between the zones. Further, the film forming apparatus includes a mechanism that supplies a raw material gas containing metal or silicon to the first zone, and a mechanism that performs sputtering of a material containing metal or silicon as a target material in the second zone.