An automatic teller machine comprising: a medium transfer portion to transfer paper mediums; a carrier position adjustment portion rotatably mounted at a rear end of the medium transfer portion; a medium carrier withdrawbly mounted in the carrier position adjustment portion to carry the paper mediums transferred by the medium transfer portion and stacked; and a sheet roller portion rotatably mounted in front of the medium carrier and the carrier position adjustment portion to transfer the paper mediums on the medium transfer portion into the medium carrier by a rotational operation and to align the paper mediums stored in the medium carrier, wherein the sheet roller portion contacts the paper medium such that a greater frictional force is generated at a middle area than an outer area when transferring the paper mediums on the medium transfer portion into the medium carrier or when aligning the paper mediums stored in the medium carrier, wherein the sheet roller portion comprises: a rotational axis; a middle sheet roller connected to the rotational axis and configured to rotate when the rotational axis rotates, such that when the rotational axis rotates at least a part of the middle sheet roller is brought into contact with a middle part of the paper mediums stored in the medium carrier; and an outer sheet roller connected to the rotational axis and configured to rotate when the rotational axis rotates, such that when the rotational axis rotates at least a part of the outer sheet roller is brought into contact with an outer part of the paper mediums stored in the medium carrier, the outer sheet roller having a smaller contact area than a contact area of the said middle sheet roller, and wherein a plurality of support portions are disposed at an outer part of the medium carrier to support part of the paper mediums disposed in the medium carrier so that the paper mediums are aligned, and wherein the plurality of support portions are disposed in positions separated toward opposite sides with respect to a middle of an outer side surface the paper mediums; and wherein the outer sheet roller is configured as a pair of outer sheet rollers, each of the pair of outer sheet rollers being disposed symmetrically at opposite sides of the rotation axis for contacting opposite side parts of the paper mediums. a medium transfer portion to transfer paper mediums; a carrier position adjustment portion rotatably mounted at a rear end of the medium transfer portion; a medium carrier withdrawbly mounted in the carrier position adjustment portion to carry the paper mediums transferred by the medium transfer portion and stacked; and a sheet roller portion rotatably mounted in front of the medium carrier and the carrier position adjustment portion to transfer the paper mediums on the medium transfer portion into the medium carrier by a rotational operation and to align the paper mediums stored in the medium carrier, a rotational axis; a middle sheet roller connected to the rotational axis and configured to rotate when the rotational axis rotates, such that when the rotational axis rotates at least a part of the middle sheet roller is brought into contact with a middle part of the paper mediums stored in the medium carrier; and an outer sheet roller connected to the rotational axis and configured to rotate when the rotational axis rotates, such that when the rotational axis rotates at least a part of the outer sheet roller is brought into contact with an outer part of the paper mediums stored in the medium carrier, the outer sheet roller having a smaller contact area than a contact area of the said middle sheet roller, and