A paper sheet processing device configured to process a plurality of paper sheets and to stack the processed paper sheets, the paper sheet processing device comprising: a processing unit configured to process the paper sheets; and at least one stacking unit configured to stack therein the paper sheets after being processed by the processing unit, wherein the stacking unit includes a stacking unit main body having a box storage space, and a storage box having a size capable of putting in and out the storage box from the box storage space, and having an opening formed in an upper part of the storage box, through which the paper sheets can pass, and a paper-sheet storage space for storing the stacked paper sheets, wherein the stacking unit further includes a placing portion having an upper surface that is wide enough to place the paper sheets thereon and arranged movably in a vertical direction inside the storage box, a placing-portion moving unit configured to move the placing portion at least upward, in a state where the storage box is stored in the box storage space, the placing-portion moving unit has a moving member (21, 35) capable of moving vertically, and the placing portion can move toward or away from the moving member (21, 35), characterized in that the paper sheet processing device further comprises a coupling unit that detachably couples the placing portion and the moving member (21, 35) with each other, wherein the coupling unit includes at least one magnet (15, 30), the magnet (15, 30) is provided in any one or both of the placing portion and the moving member (21, 35), and the magnet (15, 30) is arranged to detachably couple the placing portion and the moving member (21, 35) with each other in a state where the storage box is stored in the box storage space, and release the coupling in a state where the storage box is out of the box storage space. a processing unit configured to process the paper sheets; and at least one stacking unit configured to stack therein the paper sheets after being processed by the processing unit, wherein the stacking unit includes a stacking unit main body having a box storage space, and a storage box having a size capable of putting in and out the storage box from the box storage space, and having an opening formed in an upper part of the storage box, through which the paper sheets can pass, and a paper-sheet storage space for storing the stacked paper sheets, wherein the stacking unit further includes a placing portion having an upper surface that is wide enough to place the paper sheets thereon and arranged movably in a vertical direction inside the storage box, a placing-portion moving unit configured to move the placing portion at least upward, in a state where the storage box is stored in the box storage space, the placing-portion moving unit has a moving member (21, 35) capable of moving vertically, and the placing portion can move toward or away from the moving member (21, 35), characterized in that the paper sheet processing device further comprises a coupling unit that detachably couples the placing portion and the moving member (21, 35) with each other, wherein the coupling unit includes at least one magnet (15, 30), the magnet (15, 30) is provided in any one or both of the placing portion and the moving member (21, 35), and the magnet (15, 30) is arranged to detachably couple the placing portion and the moving member (21, 35) with each other in a state where the storage box is stored in the box storage space, and release the coupling in a state where the storage box is out of the box storage space. the stacking unit further includes a placing portion having an upper surface that is wide enough to place the paper sheets thereon and arranged movably in a vertical direction inside the storage box, a placing-portion moving unit configured to move the placing portion at least upward, in a state where the storage box is stored in the box storage space, the placing-portion moving unit has a moving member (21, 35) capable of moving vertically, and the placing portion can move toward or away from the moving member (21, 35), characterized in that the paper sheet processing device further comprises a coupling unit that detachably couples the placing portion and the moving member (21, 35) with each other, wherein the coupling unit includes at least one magnet (15, 30), the magnet (15, 30) is provided in any one or both of the placing portion and the moving member (21, 35), and the magnet (15, 30) is arranged to detachably couple the placing portion and the moving member (21, 35) with each other in a state where the storage box is stored in the box storage space, and release the coupling in a state where the storage box is out of the box storage space.