Developer cartridge, image forming unit and image forming apparatus

A developer cartridge comprising:

• an outer barrel member;
• an inner barrel member rotatably provided with respect to said outer barrel member;
• and
• a regulating member rotatably provided with respect to said inner barrel member, said regulating member including a first engaging portion and a second engaging portion,
• wherein said inner barrel member includes a first to-be-engaged portion that engages said first engaging portion and an operating member,
• wherein said outer barrel member includes a second to-be-engaged portion that engages said second engaging portion,
• wherein, when said first engaging portion and said first to-be-engaged portion engage each other, and engagement between said second engaging portion and said second to-be-engaged portion is released, said inner barrel member is rotatable together with said regulating member with respect to said outer barrel member, and
• wherein, when engagement between said first engaging portion and said first to-be-engaged portion is released, and engagement between said second engaging portion and said second to-be-engaged portion released, said regulating member is rotatable with respect to said inner barrel member.