apparatus main shutter 8 is engaged with the pair of guiding members 7 c located at the lengthwise edges of the rectangular toner reception hole 7 b on the underside of the semicylindrical top wall of the toner supply container cradle 7 a with the provision of this structural arrangement the apparatus shutter 8 is allowed to slide along the semicylindrical top wall of the toner supply container cradle 7 a along the curvature of the top wall to open or close the toner reception hole 7 b when the toner supply container 1 is not in the toner supply container cradle 7 a of the toner receiving apparatus 7 the apparatus shutter 8 is in the position shown in fig3 c in which the edge of the apparatus shutter 8 is in contact with the stopper 7 d of the toner receiving apparatus 7 keeping thereby the toner supplying hole 7 b of the toner receiving apparatus 7 closed and therefore preventing the toner from moving back into the toner supply container cradle 7 a from inside the main assembly of the image forming apparatus the apparatus shutter 8 is also provided with a pair of projections 8 a which engage with the pair of projections 6 of the toner supply container 1 during the operation for mounting the toner supply container 1 into the main assembly next referring to fig4 a and.