Provided is a drive transmission switching mechanism that can switch and drive two circulation units by one motor in response to a switching operation of a paper sheet transport direction. A paper sheet storage unit includes a first circulation unit 100 and a second circulation unit 200 that respectively receive transported paper sheets upon reception of a drive force from a single motor 302 and feed paper sheets stored therein, a sorter 310 that sorts paper sheets to either one of the circulation units, and a drive transmission switching mechanism 400 that transmits a drive force from the motor to either one of the circulation units. The drive transmission switching mechanism is activated in conjunction with an operation to change the posture of the sorter, thereby switching and transmitting the drive force to either one of the circulation units.