In response to a command from the control PC 4, the first mobile terminal test apparatus 2 compresses data of test signals including a first test signal and a second test signal which are generated and encrypted, and adds a restoration parameter to a header of the compressed data. The second mobile terminal test apparatus 3 acquires the restoration parameter-added compressed data at the second port 3a via the cable 5 from the first port 2a, and restores and encrypts the data of test signals before encryption, based on the restoration parameters. Under the control of the control PC 4, the first mobile terminal test apparatus 2 outputs the data of the first test signal to the device under test W, and the second mobile terminal test apparatus 3 outputs the data of the second test signal to the device under test W.