A chemical vapor deposition apparatus which comprises a susceptor for mounting a substrate thereon, a heater for heating the substrate, a feed gas introduction portion and a reaction gas exhaust portion, wherein a light transmitting ceramics plate held or reinforced by means of a supporting member is equipped between the heater and a mounting position of the substrate. A chemical vapor deposition apparatus that is capable of forming film stably for a long time without giving a negative influence on a quality of semiconductor film even in a case of chemical vapor deposition reaction employing a furiously corrosive gas with an elevated temperature for producing a gallium nitride compound semiconductor or so was realized.