Developing device and image forming apparatus

A developing device comprising:

• a developer container comprising a first chamber and a second chamber arranged along a lateral direction, which crosses a gravitational direction, developer circulating through the first chamber and the second chamber;
• a transporting member rotatably disposed in the first chamber, the transporting member transporting the developer in a first direction extending along an axis of the transporting member;
• and
• a supply member rotatably disposed in the second chamber, the supply member having a maximum outermost diameter smaller than a maximum outermost diameter of the transporting member, the supply member supplying the developer to a developer holding member while transporting the developer in a second direction opposite to the first direction,
• wherein, while the supply member and the transporting member are rotating, an upper surface of developer contained in the first chamber and an upper surface of developer contained in the second chamber are at levels lower than an upper-most end position of the transporting member and higher than or equal to an upper end position of the supply member in the gravitational direction, and
• wherein a bottom of the first chamber and a bottom of the second chamber in the gravitational direction are at the same level, and
• wherein a lowermost end position of the transporting member in the gravitational direction level lower than a lowermost end position of the supply member in the gravitational direction.