Development device including a removable seal to seal a supplied-developer and/or a collected-developer communicating area

A development device, comprising:

• a developer containing part containing developer;
• a developer carrier to carry, by rotation, developer that is supplied from the developer containing part to a development range;
• a partition dividing the developer containing part into a supply part and a circulation part disposed beneath the supply part to collect developer from the developer carrier;
• a first developer transport member disposed in the supply part of the developer containing part to supply developer from the supply part to the developer carrier;
• a second developer transport member disposed in the circulation part to transport developer in the circulation part in an axial direction of the developer carrier;
• and
• a bring-up opening through which developer is brought up from the circulation part to the supply part, wherein
• a length of the bring-up opening in an axial direction of the developer carrier increases as a position in a direction perpendicular to the axial direction moves away from the developer carrier.