Optical scanning device and image forming apparatus including the same

An optical scanning device includes a cooling air passage that passes through inside of the housing, a blowing part that takes in air outside of the housing from a first end portion of the cooling air passage and allowing the air to be discharged from a second side portion, the first end portion facing the second side portion, a foreign matter falling concave part provided adjacent to the transparent cover in the predetermined direction such that an accumulated foreign matter is fallen at a front side in a progress direction of the cleaning member when the cleaning member reaches each moving end of the reciprocal movement path, and a communication passage that allows the foreign matter falling concave part and the cooling air passage to communicate with each other.