A torque detection device includes an inner ring, a middle ring, an outer ring, a first beam, a second beam, a magnetic target, and a magnetic sensor. The first beam is composed of an elastic member extending in a radial direction so as to couple the inner ring and the middle ring together. The second beam is composed of an elastic member extending in a radial direction so as to couple the middle ring to the outer ring together. The magnetic target is fixed to the inner ring and the magnetic sensor is fixed to the middle ring such that the magnetic target and the magnetic sensor face each other. Torque acting on the inner ring or the outer ring is calculated according to how an amount of magnetism sensed by the magnetic sensor changes.