A developer accommodating container for accommodating a developer includes: a toner seal member for unsealably sealing an opening of the developer accommodating container; an unsealing member, connected to an end portion of the toner seal member, for unsealing the opening by moving at least a part of the toner seal member; and an auxiliary unsealing member for assisting unsealing by changing a pulling direction of the toner seal member by the unsealing member. The auxiliary unsealing member includes a shaft portion or a projected portion. The shaft portion or the projected portion extends in a longitudinal direction of the developer accommodating container.