An embodiment of the present invention relates to a dual-band filter and an operating method thereof. The dual-band filter comprises: a diplexer which enables one of a first band signal and a second band signal to be transmitted and blocks the other signal; a band pass filter which executes a band-pass filtering operation to filter the first band signal; a balun which converts the first band signal to a single signal from a differential signal when the first band signal is transmitted and converts the first band signal to a differential signal from a single signal when the first band signal is received; and a direct current (DC) supply port which supplies a DC voltage to the balun when the first band signal is received. Accordingly, the present invention can support dual band communications and simultaneously improve energy efficiency regarding transmission and reception of signals.
