A developer supply container detachably mountable to an image forming apparatus includes a first chamber, provided with a first opening, for accommodating a developer; a second chamber for receiving the developer from the first chamber through the first opening, the second chamber being provided with a second opening for permitting discharge of the developer to an outside of the developer supply container; a first sealing member for sealing the first opening; a second sealing member for sealing the second opening; and a connecting mechanism for interrelating an unsealing operation of the first opening with an unsealing operation of the second opening, while permitting a resealing operation of the second opening by said second sealing member without resealing the first opening by the first sealing member.