Image forming apparatus

An image forming apparatus for forming a toner image on a sheet, said image forming apparatus comprising:

• a main assembly;
• a first unit including a toner discharge opening;
• a second unit including a toner receiving opening, wherein at least one of said first unit and said second unit is detachably mountable to said main assembly;
• and
• a shutter configured to permit toner to move from said first unit into said second unit in a state that said at least one of said first unit and said second unit are set in said main assembly, and said toner discharge opening of said first unit is above said toner receiving opening of said second unit, said shutter being further configured to close said toner discharge opening of said first unit when said at least one of said first unit and said second unit is removed from said main assembly, wherein by inserting said at least one of said first unit and said second unit into said main assembly, said shutter is moved to a position right above said toner receiving opening of said second unit or at least a predetermined part of a sealing member for said toner receiving opening, and thereafter, said shutter is opened by a further insertion of said at least one of said first unit and said second unit.