A gear transmission is provided with a gear structure and a plurality of motors. The gear structure is provided with a plurality of crank shafts, an eccentric rotation gear, and a rotation gear. Each motor is attached to one of the crank shafts. At least one of the plurality of motors is a first motor, and at least another of the plurality of motors is a second motor. The second motor has a length in an axial direction shorter than that of the first motor.