A developer supply container 1 is detachably mountable to a developer receiving apparatus including a developer receiving portion 11 provided with a receiving port 11a for receiving a developer, a portion-to-be-engaged 11b a displaceable integrally with the developer receiving portion 11. The developer supply container 1 includes an engaging portion 30 and a discharging portion provided with a shutter opening 4j for discharging the developer accommodated in a developer accommodating portion. The engaging portion 30 is provided at only one side with respect to a predetermined direction crossing with a mounting direction of the developer supply container 1 in the crossing with a displacing direction of the developer receiving portion 11. The engaging portion 30 engages with the portion-to-be-engaged 11b with a mounting operation of the developer supply container 1 to bring the receiving port 11a in the communication with the shutter opening 4j.