An automatic teller machine (ATM) may include a medium transfer portion to transfer paper mediums from a paper medium storage portion storing the paper mediums, a carrier position adjustment portion rotatably mounted at a rear end of the carrier transfer portion, to which a medium carrier stacking and carrying the paper mediums transferred along the medium transfer portion is rotatably mounted, and a sheet roller portion rotatably mounted between 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.