The present invention relates to an input/output signal synchronization method by a radio frequency unit. The input/output signal synchronization method according to the present invention comprises the steps of: generating a transmitter (Tx) input signal by adding, to a baseband signal, a test signal located at a frequency out of an operation frequency range of the radio frequency unit; collecting the Tx input signal and a Tx output signal obtained by outputting the input signal through a Tx function block; and synchronizing the Tx input signal and the Tx output signals, based on a result obtained by the collecting.