A differential amplifier comprises first, second, and third input terminals (1, 2, and 3), output terminal (4), first and second differential pairs (531 and 532) (533 and 534) driven by a corresponding current source and having output pairs commonly connected to load circuits (537 and 538), and an amplifier stage (539) having input end connected to at least one of the common connection points of the load circuits and output pairs of the first and second differential pairs and output end connected to output terminal. Input pair of second differential pair receives a signal from third input terminal and a feedback signal from output terminal. First and second switches (SW1 and SW2) are provided between the input pair of the first differential pair and the first and second input terminals (1 and 2), and first and second capacitors (C1 and C2) connected between each connection point of the input pair of the first differential pair and the first and second switches (SW1 and SW2) and a reference voltage terminal are provided. The first, second and third input terminals (1, 2, and 3) may be combined into one terminal to which voltages are serially supplied. It avoids the influence of power supply/signal noise and switch noise, and provides operational output from a plurality of input reference voltages.