Medium processing device and medium transaction device

A medium transaction device comprising:

• an operation display section that displays operation screens during a transaction with a user;
• a pay-in/pay-out port into which banknotes are inserted by the user, and that dispenses banknotes to be paid out to the user;
• a conveyance section that conveys a sheet-shaped medium for transaction with the user along a conveyance path;
• a drive transmission section that transmits drive force to the medium so as to cause the medium to travel along the conveyance path;
• an operation knob that is provided on an operation side face of the conveyance section, and that is used for operating the drive transmission section;
• and
• a storage box that stores the medium therein, and that is capable of transitioning between an opposing state in which the storage box opposes the operation side face of the conveyance section over a range including at least the operation knob, and a non-opposing state in which the storage box does not oppose the operation side face.