The present invention relates to a control circuit system of a pair of mobile terminals comprising a first mobile terminal and a second mobile terminal. The first mobile terminal comprises a first display unit, a first fastening unit, a proximity sensor for recognizing a connection with the second mobile terminal, and a first control circuit including a first near-field communication module and a first signal aggregator for transmitting/receiving a signal to and from the second mobile terminal. The second mobile terminal comprises a second display unit, a second fastening unit connected to the first fastening unit, and a second control circuit including a second near-field communication module and a second signal aggregator for transmitting/receiving a signal to and from the first mobile terminal. A signal transmitted from the first near-field communication module is received by the second near-field communication module and displayed on the second display unit.