The developing device includes: a developing container for storing a developer; first and second conveying passages that are formed in the developing container and sectioned by a partition; first and second conveying members disposed inside the first and second conveying passages, respectively, to agitate and circulatively convey the developer through the first and second conveying passages in opposite directions; a developing roller that supplies the developer in the second developer conveying passage to a photoreceptor drum; first and second communication paths that connect between the first and second conveying passages at both ends of the partition; and, a developer flow regulator that regulates the flow of developer moving from the first conveying passage to the second conveying passage, in accordance with the height of the developer surface of the developer.