The mobile electronic device is provided with: a first communication unit which performs communication; an operation unit which includes a plurality of first keys having numbers assigned respectively thereto; a display unit which, in response to the operation of at least one of the plurality of first keys, displays the number assigned to the first key that was operated; and a control unit which, if a passcode request signal is received from the first communication unit at the same time that the number selected by operating one of the first keys while a reference screen was displayed on the display unit is being displayed on the display unit, controls so that the number sequence displayed on the display unit is transmitted to the unit that transmitted the passcode request signal by the first communication unit.