An amplifying apparatus includes a first amplifier that amplifies a first signal of a constant amplitude; a second amplifier that amplifies a second signal identical in amplitude and differing in phase with respect to the first signal; a first transmission line of which, a first end is connected to an output terminal of the first amplifier; a second transmission line differing in length with respect to the first transmission line and of which, a first end is connected to an output terminal of the second amplifier and a second end is connected to a second end of the first transmission line; and an amplitude balance adjusting element connected to the first or the second transmission line. The amplifying apparatus outputs from a connection node of the first and the second transmission lines, a signal that is a combination of output signals of the first amplifier and of the second amplifier.