To provide a developing apparatus that can achieve efficient aeration structure and can reduce the cost.

The developing apparatus has two or more chambers including a retention chamber 25 where a gas generating from a processing liquid to develop a photosensitive material is retained, and a controlling chamber 61 having a controlling device 6 to control development, wherein connecting ports 94 are formed in some chambers including the retention chamber 25 and the controlling chamber 61, in addition, an air suction port 91 and air discharge port 92 are provided to form an air flow passage 9 to dispose the retention chamber 25 to be in a downstream side of the controlling chamber 61, and only the air discharge port 92 in the air flow passage 9 is equipped with a fan 93.