Developing device

A developing device which can be attached to an image forming apparatus, comprising:

• a developer accommodating portion configured to accommodate developer;
• a developing portion having a rotatable developer carrying member configured to bear the developer;
• and
• an agitating member disposed in the developer accommodating portion and configured to agitate the developer in the developer accommodating portion, wherein
• the developer accommodating portion and the developing portion are connected to each other via an opening portion;
• before the developing device is attached to the image forming apparatus, a sealing sheet connected to the agitating member is fixed to a fixing portion in a periphery of the opening portion such that the opening portion is sealed;
• after the developing device is attached to the image forming apparatus, the agitating member is operated, and the sealing sheet is removed from the fixing portion such that the developer accommodating portion and the developing portion communicate with each other;
• wherein, a direction in which a rotation axis of the agitating member extends is a first direction, a projecting portion is provided on a downstream side of the fixing portion and on an upstream side of the opening portion in a second direction crossing the first direction;
• and
• a height of the projecting portion is higher than at least a part of a height of a fixing-position projecting portion formed at a fixing position.