Developer supply device

A developer supply device, comprising:

• a carrying substrate having a plurality of electrodes arranged along a developer transport path at predetermined intervals to carry a developer along the developer transport path through a traveling electric field,
• wherein the carrying substrate comprises:
• an upper carrying substrate that is formed of a rigid substrate and is formed to stand to carry the developer upward;
• and
• a bottom carrying substrate that is formed of a flexible substrate curved to be a semispherical shape when viewed as a side cross section, and is configured to charge the developer by friction with the developer and to be connected with a lower end portion of the upper carrying substrate so as to form a bottom surface of a developer reservoir portion,
• wherein a joint portion of the bottom carrying substrate which is an end where the bottom carrying substrate is connected to the lower end portion of the upper carrying substrate is overlapped with the lower end portion of the upper carrying substrate such that the joint portion carries the developer in a same direction as a direction in which the developer is carried by the lower end portion of the upper carrying substrate.