A nozzle insertion member arranged in a powder container includes a nozzle insertion opening; an opening/closing member opening/closing the nozzle insertion opening; a supporting member supporting the opening/closing member; and a biasing member provided to the supporting member to bias the opening/closing member toward a closing position. When the powder is supplied to the conveying nozzle along with rotation of a rotary conveyor arranged inside the powder container, the supporting member rotates with the rotation of the conveyor. The opening/closing member is rotated by a drive transmitting mechanism with rotation of the supporting member. The mechanism includes an elongated member arranged on the opening/closing member and penetrating through an opening formed on the supporting member; and a drive transmitted portion formed on the elongated member; and a drive transmitting portion formed on an inner surface of the opening and configured to come into contact with the drive transmitted portion.