A mobile telephone includes an expansion slot to which an expansion display unit is attached by insertion in a way as to be capable of being taken out and put in freely. The expansion display unit is provided with an expansion display section having a display surface larger than that of the main body display section of the mobile telephone. The mobile telephone then displays information on the expansion display section. The large display surface of the expansion display section can display most of the contents of the information to be displayed collectively, which makes it easy to confirm the contents of the information to be displayed and improves the usability of the mobile telephone.