The present invention relates to. The operating system conversion device for a mobile terminal operates by means of a first operating system (OS), and, when connected to a vehicle, operates by means of an agent, the operating system conversion device comprising: a reception unit which receives, from the vehicle, a second operating system which is different from the first operating system and is exclusively used for the vehicle during connection with the vehicle; and a conversion unit which, during connection with the vehicle, converts the operating system from the first operating system to the second operating system.