The present invention relates to a broadcast signal receiver comprising a low noise amplifier for receiving an RF signal and selectively amplifying the received RF signal; a tuner for tuning the RF signal selectively amplified by the low noise amplifier to a predetermined channel; a signal analyzer for demodulating a signal output from the tuner and calculating a signal-to-noise ratio of the demodulated signal; and a controller for determining the strength of the signal output from the tuner, and controlling a selective amplifying operation of the low noise amplifier on the basis of the determined signal strength and the signal-to-noise ratio. Thus, the present invention provides a broadcast signal receiver and a control method thereof, which prevents poor picture quality when the LNA is turned on due to the RF signal having a weak electric field.