Disclosed is a differential power amplifier using mode injection, which includes: a first transistor of which the gate receives a first signal and the source is connected to the ground; a second transistor of which the gate receives a second signal and the source is connected to the ground; a third transistor of which the source is connected to the source of the first transistor; a fourth transistor of which the source is connected to the source of the second transistor; a fifth transistor of which the source is connected with the drain of the first transistor and the drain is connected with a first output port and the drain of the third transistor; and a sixth transistor of which the source is connected with the drain of the second transistor and the drain is connected with a second output port and the drain of the fourth transistor.