The present invention provides a medium protection device and a medium separating and stacking device capable of avoiding damage to a medium when moving the medium along a guide. In a banknote cassette, a guide body is attached to a circumferential side face of a central body of a tongue piece roller in a range not provided with tongue pieces. When feeding out banknotes, the banknote cassette stops the tongue piece roller in a retracted state, thereby positioning an outer circumferential face of the guide body in the vicinity of the surface of a front upper curved portion of a hole in the conveyance guide, such that the hole can be placed in an almost completely blocked state. The present invention can accordingly prevent the vicinity of a corner of a banknote from entering the hole, enabling creasing during conveyance to be forestalled.