A communication terminal apparatus such as a portable telephone apparatus has a main body, a selection operation unit, an operation inputting unit, a display unit, and a controller. The main body has a speaker and a microphone. The selection operation unit is provided on the main body and selects one mode from a plurality of modes of the communication terminal apparatus. The operation inputting unit is provided on the main body and changes functions based on the mode selected by the selection operation unit. The display unit is provided on the main body and displays information required for selection operation or inputting operation by the selection operation unit and/or the operation inputting unit. The controller sets a mode selected based on the input from the selection operation unit, and switches a function of the operation inputting unit based on the input from the selection operation unit. The controller controls display operation of the display unit based on the input from the selection operation unit and/or the operation inputting unit.