A multi-banknote cassette, which is installed in an ATM (Automated Teller Machine) and stores various kinds of banknotes at the same time, comprising: a cassette body having a banknote entrance/exit formed at one side thereof, and including an internal storage space for storing banknotes; a separator/stacker installed at the banknote entrance/exit of the cassette body, and stacking banknotes carried into the cassette body in the storage space or separating banknotes discharged from the cassette body one by one and transferring the separated banknotes; a banknote stopper installed on the opposite wall surface of the side at which the separator/stacker is installed, in the cassette body; a stack guide installed at the top of the storage space, and guiding the banknotes introduced into the storage space by the separator/stacker toward the banknote stopper; characterized in that the multi-banknote cassette further comprises a movable stopper rotatably installed in the stack guide, and rotated to retreat into the stack guide or protrude from the stack guide, wherein when a banknote introduced into the storage space has a relatively small size, the movable stopper is rotated to protrude from the stack guide, and regulates the front end of the introduced banknote, and when a banknote introduced into the storage space has a relatively large size, the movable stopper is rotated to retreat into the stack guide and the banknote stopper regulates the front end of the introduced banknote, such that various kinds of banknotes having different sizes are aligned and stacked in the storage space, wherein the movable stopper is rotated to retreat into the stack guide or protrude from the stack guide according to the size of a banknote introduced into the storage space, based on banknote detection information of a banknote detection part installed in the ATM. a cassette body having a banknote entrance/exit formed at one side thereof, and including an internal storage space for storing banknotes; a separator/stacker installed at the banknote entrance/exit of the cassette body, and stacking banknotes carried into the cassette body in the storage space or separating banknotes discharged from the cassette body one by one and transferring the separated banknotes; a banknote stopper installed on the opposite wall surface of the side at which the separator/stacker is installed, in the cassette body; a stack guide installed at the top of the storage space, and guiding the banknotes introduced into the storage space by the separator/stacker toward the banknote stopper; characterized in that the multi-banknote cassette further comprises a movable stopper rotatably installed in the stack guide, and rotated to retreat into the stack guide or protrude from the stack guide, wherein when a banknote introduced into the storage space has a relatively small size, the movable stopper is rotated to protrude from the stack guide, and regulates the front end of the introduced banknote, and when a banknote introduced into the storage space has a relatively large size, the movable stopper is rotated to retreat into the stack guide and the banknote stopper regulates the front end of the introduced banknote, such that various kinds of banknotes having different sizes are aligned and stacked in the storage space, wherein the movable stopper is rotated to retreat into the stack guide or protrude from the stack guide according to the size of a banknote introduced into the storage space, based on banknote detection information of a banknote detection part installed in the ATM.