An amplifier includes: a single-stage or multiple-stage variable gain amplifier that amplifies an input signal with a controlled gain; a AGC control circuit that detects the peak level of a signal outputted from the variable gain amplifier in the final stage, converts the resultant signal to a digital signal, and outputs an AGC control signal for controlling the gain of the variable gain amplifier based on the converted digital signal; an EVR control circuit that outputs an EVR control signal according to a signal of setting an attenuation value or an amplification value for EVR inputted from an electronic variable resistor control terminal; and a gain control circuit that controls the gain of the variable gain amplifier in accordance with at least one of the AGC control signal and the EVR control signal. The occurrence of “popping” sounds caused by differences in DC voltage due to switching between an AGC circuit and an electronic variable resistor circuit can be suppressed.