Medium transfer device and automatic paper currency deposit/withdrawal machine

Provided is a paper-currency transfer device, which prevents paper-currency clogging in a paper-currency transfer unit composed of a plurality of transfer units and which neither has a complicated structure nor needs a dedicated drive source. A medium transfer device transfers a medium from a sending-side paper-currency transfer passage as a first transfer passage to a receiving-side paper-currency transfer passage as a second transfer passage. The medium transfer device comprises a runner mounted coaxially with a transfer roller on a receiving side of the receiving-side paper-currency transfer passage. The runner is rotated at a higher speed than that of the transfer roller on the receiving side. The drive source of the runner is common to that of the transfer roller.