The torque detection apparatus detects torque using torsion of a torsion bar. The torque detection apparatus includes a first rotating shaft and a second rotating shaft connected with a torsion bar in which torsion is produced when torque is applied, at least one optical scale that moves with rotations of the first rotating shaft and the second rotating shaft, at least one optical sensor that is paired with the optical scale, and detects the polarization of transmissive light or reflected light, the polarization varying depending on a position where light source light is passed through or reflected on the optical scale, and a computing unit that computes a relative rotational angle of the optical scale with respect to the optical sensor, and computes rotational displacements of the first rotating shaft and the second rotating shaft.