The invention discloses an apparatus for measuring the torsion between a first point (41) and a second point (42) of a test object (1), said second point being spaced apart from the first point. The apparatus comprises the following: a source of polarized light, comprising a polarizing light source (15) that emits polarized light, or a polarizer (20) that is connected to a light source (10) by way of an optical feed; a first optical fibre (40) that is optically connected to the Output of the polarizing light source (15) or to the Output of the polarizer (20) and that is fastened to the test object (1) at the first point (41) and at the second point (42) in such a way that a torsion of the test object about a torsion axis causes a change in the angle of rotation of the first optical fibre from the first point in relation to the second point, and a second polarization-maintaining optical fibre (50), that is connected to the first optical fibre (40) at the second point (42) or downstream of the second point (42) in relation to the light path Coming from the source, for supplying the light to a measuring device (30, 31), wherein the distance between the first point (41) and the second point (42) of the test object (1) is greater than or equal to 5 metres, or greater than or equal to 7 metres, or greater than or equal to 10 metres, and the first optical fibre (40) comprises a non-polarization-maintaining, bending-insensitive fibre.