PURPOSE: To eliminate the need for an exclusive use LED or LCD for displaying battery residual capacity by using a lighting section of a lighting dial key for the display of the battery residual capacity differently from that for the use of the dial key.

CONSTITUTION: A control means 7 subtracts a quantity of current consumption in the standby mode × standby time from the charging quantity of a battery when the standby mode is finished, displays how many % the current battery charge quantity are in the beginning of the talking mode, where 100% are the full charging capacity of the battery, and sets a timer. Then a change in the mode from the talking mode is checked and when the talking is finished, the quantity of consumed current × talking time in the talking state is subtracted from the charging quantity of the battery and the timer is set in the charging state. Furthermore, a change in the mode is checked from the charging state, and when the charging is finished, the quantity of charging current × charging time is added to the charging quantity of the battery. The residual capacity obtained in this way is displayed by lighting relevant numerals of a dial key 6 with a LED 6.