A developing device includes a bottom cover part that covers a bottom surface of a developing container and forms an air passage extending in a front and rear direction between the bottom surface and the bottom cover part, an air blowing fan that supplies air into the air passage, and an air receiving port that is provided at a front end part of the air passage and receives the air supplied from the outside of the air passage by the air supply unit. Air discharge ports are provided on wall parts on both right and left sides forming the air passage and discharge the air flowing into the air passage to the outside of the air passage.