A sound volume control circuit includes: a first operational amplifier; a variable resistor circuit connected between an output and an inverting input of the first operational amplifier and having a plurality of resistance values; an R-2R ladder circuit connected between a voltage source of an input voltage; and a control circuit controlling the variable resistor circuit and the R-2R ladder circuit; wherein when changing a resistance value of the variable resistor circuit from a first resistance value to a second resistance value, so as to change the output voltage in a step size where a difference between the output voltage corresponding to the first resistance value and the output voltage corresponding to the second resistance value is further segmented, the control circuit changes the magnitude of the electric current flowing to the variable resistor circuit by use of the R-2R ladder circuit.