A mobile terminal device equipped with radio communicating portions capable of holding a radio communication in accordance with a predetermined communication standard, and a standard signal outputting portion for outputting a signal in a format based on a predetermined signaling system to any display device prepared on an outside, includes a communication standard detecting means for detecting a type of the communication standard selected based on operating conditions of radio communicating portions, when one of the radio communicating portions conforms to plural types of communication standards or when a plurality of radio communicating portions conform to plural types of communication standards respectively, and a signaling system selecting means for selecting automatically a signaling system of the signal that the standard signal outputting portion outputs, in response to the type of the communication standard that the communication standard detecting means detects.