To provide a mobile terminal apparatus with the lower communication cost in sending a log at the occurrence of a malfunction, abnormality or fault in the mobile terminal apparatus to a network. A diagnostic process for the malfunction is performed in accordance with a diagnostic policy acquired from the outside. An error code corresponding to the diagnostic result is generated. The generated error code is outputted. With an automatic fault diagnostic function of automatically analyzing the fault in the mobile terminal apparatus without directly sending the log collected in the mobile terminal apparatus to an analytic server, the communication cost can be reduced.