A developing device is disclosed which includes a developing tank, a developing roller, a carrying member, and a filter. Rotation of the developing roller causes a first airflow directed from the outside of the developing tank through an air path to the inside of the developing tank. Rotation of the carrying member causes a second airflow directed from below in an upward direction inside the developing tank. Collision between the first airflow and the second airflow causes a third airflow directed from the inside of the developing tank through the filter to the outside of the developing tank and further from the outside through the filter back to the inside of the developing tank. This arrangement prevents not only filter clogging but also a toner leak to the outside of the developing device.