There is provided a film forming apparatus for performing a film forming process on substrates by heating the substrates while the substrates are held in a shelf shape by a substrate holder in a vertical reaction container. The film forming apparatus includes: an exhaust part configured to evacuate the reaction container; a gas supply part configured to supply a film forming gas into the reaction container; a heat insulating member provided above or below an arrangement region of the substrates to overlap with the arrangement region and configured to thermally insulate the arrangement region from an upper region above the arrangement region or a lower region below the arrangement region; and a through-hole provided in the heat insulating member at a position overlapping with central portions of the substrates to adjust a temperature distribution in a plane of each substrate held near the heat insulating member.