In a film forming method wherein gas cooling is employed, deterioration of a film forming rate and excessive load on a vacuum pump due to gas introduction are eliminated, while achieving sufficient cooling effects. The thin film forming apparatus is provided with a cooling body (10) arranged close to the rear surface of a substrate (7) in a thin film forming region (14); a gas introducing means for introducing a gas into between the cooling body (10) and the rear surface of the substrate (7); and a gap maintaining means (11), which is brought into contact with the rear surface of the substrate (7), divides the thin film forming region (14) into a first thin film forming region (14a) and a second thin film forming region (14b) having a film forming speed lower than that of the first region (14a), and maintains a gap between the cooling body (10) and the substrate (7). Cooling conditions are set so that a cooling quantity in the first region (14a) is larger than that in the second region (14b).