To provide communication regulator and regulating method of a portable terminal such as a portable telephone in which use regulation of the portable terminal can be optimized furthermore.

A telephone conversation suppression determination section determines whether an accessory power supply Acc from a vehicle is turned on or off (step 101). When the accessory power supply Acc is turned on, the telephone conversation suppression determination section determines whether a parking brake is turned on or off from the Parking signal of the vehicle (step 102). When the parking brake is turned off, the telephone conversation suppression determination section determines whether a handsfree device is connected with it or not (step 103). When the handsfree device is connected, the telephone conversation suppression determination section instructs telephone conversation suppression to a jammer (step 104).