PURPOSE: To reduce and simplify a circuit scale and to make the circuit economical by scanning dial keys and a touch panel with a common scanning line by a central control part in a telephone set provided with dial keys and the touch panel and stopping the operation if the touch panel if the power failure of a commercial power source occurs.

CONSTITUTION: A scanning line 100 is provided which scans dial keys 12 and a touch panel 13 together. A central control part 11 scans dial keys 12 through the scanning line 100 to discriminate a depressed dial button and sends information to a line control part 19 to send a corresponding dial number. The control part 11 scans the touch panel 13 through the scanning line 100 to discriminate a closed switch and sends information to the line control part 19 to execute a corresponding function, for example, one-touch dialing. In case of a power failure of the commercial power source, the scanning of the touch panel is stopped by a disconnecting part 11F which receives an instruction from a power supply part 15 fed by the commercial power source, but the dial number sending function based on the scanning of dial keys 12 through the scanning line 100 is held by power supply from a power supply part 14 fed by a subscriber's line.