To improve the safety of driving by allowing a telephone system to make automatic reply, while a driver conducts driving operations such as control of the steering wheel or acceleration/deceleration.

This system is provided with an external connection terminal 2, to which a cellular telephone set or portable telephone set 1 is connected, a reply control section 4 that executes automatic reply processing, a changeover control section 6 that sends/receives a signal between the telephone set 1 and the reply control section 4, a recording/reproducing section 5 that records/ reproduces a message in the case of automatic reply, and plural sensors 7 that sense a drive state of an automobile. There are a vehicle velocity sensor 7A, an acceleration sensor 7B, a direction sensor 7C, a vertical vibration sensor 7D, an oncoming vehicle sensor 7E, and a visual field analysis sensor 7F as the plural sensors. The reply control section 4 drives the recording/reproducing section 5 to make automatic reply processing, when the section 4 receives a sensing output of a sensor or more among the plural the sensors 7, denoting it that the vehicle in a driving condition is detected for which a speech by the driver is not proper.