Patent ID: 8099015

Claim:
A developer container comprising: a housing that has a developer containing part and an opening, the developer containing part containing a developer, and the opening allowing the developer to flow through; a sheet member that is provided in the housing, seals the opening from inside the developer containing part when unused, and is pulled out in one direction to open the opening when used; and a loosening regulation unit that presses a part of the sheet member to the housing, wherein the housing has a guide hole, the guide hole allowing the sheet member to be inserted in when sealing the opening with the sheet member, and guiding the sheet member when the sheet member is pulled out; the sheet member is folded back to the housing, and is constituted of a forward part and a backward part, the forward part extending from a base end to a part at which the sheet member is folded, and the backward part overlapping the forward part from the folded part and having a free end protruding outside the housing through the guide hole; a part of the loosening regulation unit is fixed to the housing, the part being at an opposite side of the guide hole in relation to the folded part; and another part of the loosening regulation unit presses at least a part of the forward part and the back part including the folded part.