[0089]Meanwhile, the main body side shutter 590 has a shutter main body 593, which is contained within the gap 584 of the slidable member 580 and is slidable in the insertion direction and the withdrawal direction of the powder cartridge 200Y, and a first swing piece 591 swingable in an approaching direction and a separating direction with respect to one of the two facing portions 583. A second swing piece 592 is also provided, which is swingable in an approaching direction and a separating direction with respect to the other one of the two facing portions 583. The first swing piece 591 and the second swing piece 592 are fastened to the upper surface of the shutter main body 593.