A torque detection device comprising: a permanent magnet; a magnetic yoke which is disposed in a magnetic field formed by the permanent magnet and a position of which relative to the permanent magnet is variable in accordance with a torsional angle of a torsion bar; a tubular magnetism collection unit that has a tubular magnetism collection holder, a magnetism collection ring, and a tubular magnetic shield covering the outer peripheries at the magnetism collection rings (71a, 71b), the magnetism collection holder being composed of a first magnetism collection holder and a second magnetism collection holder, which are disposed adjacent to each other in an axial direction of the tubular magnetism collection unit and assembled to each other, to surround the magnetic yoke, the magnetism collection ring being attached to an inner peripheral surface of the magnetism collection holder to collect magnetic flux of the magnetic yoke, and the magnetic shield being fitted with an outer peripheral surface of the magnetism collection holder to be attached; and a magnetic sensor that detects magnetic flux from a magnetic circuit formed by the permanent magnet, the magnetic yoke, and the magnetism collection ring, characterized in that the first magnetism collection holder is provided with a first positioning recessed portion and a first protrusion that projects toward the second magnetism collector holder, and the second magnetism collection holder is provided with a second protrusion at its outer peripheral surface and a second positioning recessed portion at its inner peripheral surface, the second protrusion being inserted into the first positioning recessed portion without clearance and the first protrusion being inserted into the second positioning recessed portion without clearance with the first magnetism collection holder and the second magnetism collection holder assembled to each other. a permanent magnet; a magnetic yoke which is disposed in a magnetic field formed by the permanent magnet and a position of which relative to the permanent magnet is variable in accordance with a torsional angle of a torsion bar; a tubular magnetism collection unit that has a tubular magnetism collection holder, a magnetism collection ring, and a tubular magnetic shield covering the outer peripheries at the magnetism collection rings (71a, 71b), the magnetism collection holder being composed of a first magnetism collection holder and a second magnetism collection holder, which are disposed adjacent to each other in an axial direction of the tubular magnetism collection unit and assembled to each other, to surround the magnetic yoke, the magnetism collection ring being attached to an inner peripheral surface of the magnetism collection holder to collect magnetic flux of the magnetic yoke, and the magnetic shield being fitted with an outer peripheral surface of the magnetism collection holder to be attached; and a magnetic sensor that detects magnetic flux from a magnetic circuit formed by the permanent magnet, the magnetic yoke, and the magnetism collection ring, characterized in that the first magnetism collection holder is provided with a first positioning recessed portion and a first protrusion that projects toward the second magnetism collector holder, and the second magnetism collection holder is provided with a second protrusion at its outer peripheral surface and a second positioning recessed portion at its inner peripheral surface, the second protrusion being inserted into the first positioning recessed portion without clearance and the first protrusion being inserted into the second positioning recessed portion without clearance with the first magnetism collection holder and the second magnetism collection holder assembled to each other.