Provided is a developing device including: a first helical blade; a second helical blade formed at the same blade pitch as a blade pitch of the first helical blade; a developer discharge port for discharging surplus developer; and a regulating member formed in a reverse phase with respect to the first helical blade. When a proximity portion is at a position facing a communication portion, a blade apex portion of the second helical blade is arranged to fall within a range of from a position facing an end surface portion of the communication portion on a downstream side of the second conveyance path to a position immediately before a position facing the proximity portion, which is reached in accordance with a phase shift of the second helical blade. A first stirring member and a second stirring member are driven at the same rotational speed.