A switching transformer includes a drive amplifier configured to output an input signal by amplifying a source signal, a primary circuit including a set of primary inductors, a primary switch, and a first primary connecting wire, the set of primary inductors being configured to receive the input signal at a first primary input/output terminal, the primary switch being configured to adjust an inductance of the set of primary inductors based on a first switching operation, and the first primary connecting wire being configured to electrically connect the first primary input/output terminal to an end of the primary switch, and a secondary circuit configured to mutually electrically couple to the first primary connecting wire and at least one primary inductor among the set of primary inductors.