A compound semiconductor device includes a heterojunction bipolar transistor and a bump. The heterojunction bipolar transistor includes a plurality of unit transistors. The bump is electrically connected to emitters of the plurality of unit transistors. The plurality of unit transistors are arranged in a first direction. The bump is disposed above the emitters of the plurality of unit transistors while extending in the first direction. The emitter of at least one of the plurality of unit transistors is displaced from a center line of the bump in the first direction toward a first side of a second direction which is perpendicular to the first direction. The emitter of at least another one of the plurality of unit transistors is displaced from the center line of the bump in the first direction toward a second side of the second direction.