A developer container includes a developer accommodating portion, a rotatable member, and a flexible sheet member. The developer container further includes an elastically deformable elastic member. With respect to a longitudinal direction of the developer accommodating portion, between an end portion of the rotatable member and an inside surface of the developer accommodating portion, a gap is formed to permit movement of the rotatable member relative to the developer accommodating portion. In an unused state, the sheet member is elastically deformable together with the elastic member by the movement of the rotatable member relative to the developer accommodating portion in the longitudinal direction.