A work machine includes a lower-part traveling body, an upper-part turning body, an arm, a boom, a cab, an engine, a fuel tank, and a counterweight. The upper-part turning body is turnably disposed on the lower-part traveling body. The boom has a first end connected to the upper-part turning body and a second end connected to the arm. The cab is mounted on a front left of a frame of the upper-part turning body. The engine is disposed behind the cab on the frame. The fuel tank is disposed behind the engine on the frame. The counterweight is disposed behind the fuel tank on the frame. The fuel tank is disposed in a hollow formed in the counterweight.