A CATV tuner apparatus includes a first low-noise amplifier which amplifies a level of an input signal received at an input terminal, the first low-noise amplifier having an adequately small noise figure to allow the received input signal to be amplified with no substantial degradation of a carrier-to-noise ratio of the input signal. An automatic gain control detects the level of the signal amplified by the first low-noise amplifier and adjusts an amplitude of the signal before passing the signal through the automatic gain control. A band-pass filter eliminates out-of-band signal components from the signal received from the automatic gain control and passes only in-band signal components through the band-pass filter. A second low-noise amplifier amplifies a level of the signal received from the band-pass filter. A frequency synthesizer produces an intermediate frequency signal at an output terminal through a multiplication of a frequency of the signal, amplified by the second low-noise amplifier, by an oscillation frequency.