A developing apparatus includes a sealing sheet to seal an opening portion in a developing container, an attaching portion provided on an accommodating chamber and to which the sealing sheet is attached, and a discharge portion through which the sealing sheet is discharged from inside of the developer container to outside of the developer container. The initial developer in the accommodating chamber moves to a second chamber through the opening portion by discharging the sealing sheet through the discharge portion from the inside of the developer container to the outside of the developer container. The discharge portion is disposed upstream from the opening portion and above the opening portion, and the discharge portion is disposed on a wall surface of the developer container intersected with a side wall of the developer container, the side wall having a through hole which a second conveyance screw penetrates.

A developer accommodating unit includes: a developer accommodating member, provided with an opening for permitting discharge of a developer, for accommodating the developer; a sealing member including a connecting portion for being connected to the developer accommodating member so as to seal the opening; and an unsealing member for exposing the opening by moving the sealing member to peel the connecting portion from the developer accommodating member. The connecting portion includes a first connecting portion and a second connecting portion with respect to a longitudinal direction thereof. When the connecting portion is peeled from the developer accommodating member, the unsealing member is flexed so that the first connecting portion is peeled earlier than the second connecting portion.

An image forming apparatus includes a developing device that is mountable and dismountable and has a sealing member for sealing to be removed at a time of start using the developing device. The image forming apparatus further includes a winding shaft, a drive source, a detector, and a controller. The winding shaft rotates for removal processing for removing the sealing member. The drive source drives the winding shaft. The detector detects a value corresponding to a load torque applied to the drive source. The controller notifies of an error in a case where the value detected by the detector has become smaller than a predetermined value before a predetermined period of time elapses from start of the drive by the drive source.

When a cartridge is in a posture in which it is installed in an image forming apparatus and used for image formation, a developing chamber is positioned below a storage chamber. At least a portion of an opening is located above a supply roller. A stirring shaft is located above the opening. A second stirring sheet member is provided on the side opposite to a first stirring sheet member with respect to an imaginary line passing through the center of rotation of the stirring shaft. The first stirring sheet member and the second stirring sheet member each have a length that allows the other ends thereof to reach the opening when the stirring shaft rotates.