Disclosed is a differential amplifier comprising first and second terminals for receiving signals; a third terminal for outputting a signal; first and second differential pairs, each having an input pair and an output pair, said first and second differential pairs being supplied with currents from current sources associated therewith, respectively; a load circuit connected to output pairs of said first and second differential pairs; an amplifier stage for receiving, as an input, a signal of at least one connection node of a connection node pair of said load circuit and output pairs of said first and second differential pairs, said amplifier stage having an output connected to said third terminal; and a connection switching circuit for controlling the switching between a first connection state in which first and second inputs of the input pair of said first differential pair are connected to said first terminal and said third terminal, respectively, and in which first and second inputs of the input pair of said second differential pair are connected to said second terminal and said third terminal, respectively, and a second connection state in which the first and second inputs of the input pair of said first differential pair are connected to said third terminal and said second terminal, respectively, and in which the first and second inputs of the input pair of said second differential pair are connected to said third terminal and said first terminal, respectively.