A torque detection apparatus comprising: a permanent magnet in which magnet poles are arranged in a circumferential direction; a magnetic yoke formed of a magnetic substance and disposed in a magnetic field formed by the permanent magnet so as to surround the permanent magnet, the magnetic yoke rotating relative to the permanent magnet to change a relative phase between the permanent magnet and the magnetic yoke; a magnetic element (61, 62) disposed around the magnetic yoke to output a signal corresponding to a magnetic flux from a magnetic circuit including the permanent magnet and the magnetic yoke; a signal retrieval member electrically connected to the magnetic element (61, 62); and a unit housing that is formed of resin, houses the permanent magnet and the magnetic yoke, and that is molded integrally with the magnetic element (61, 62) and the signal retrieval member so as to cover the magnetic element and the signal retrieval member; wherein the unit housing includes a body portion provided with an internal space in which the permanent magnet and the magnetic yoke are housed; and a connector portion provided with an internal space in which an end of the signal retrieval member exposed from the resin is disposed, and in the unit housing, a communication path is formed through which the internal space in the body portion is in communication with the internal space in the connector portion, characterized in that said communication path is adapted to allow air to pass from the internal space in the body portion of the unit housing to the internal space in the connector portion of the unit housing through the communication path. a permanent magnet in which magnet poles are arranged in a circumferential direction; a magnetic yoke formed of a magnetic substance and disposed in a magnetic field formed by the permanent magnet so as to surround the permanent magnet, the magnetic yoke rotating relative to the permanent magnet to change a relative phase between the permanent magnet and the magnetic yoke; a magnetic element (61, 62) disposed around the magnetic yoke to output a signal corresponding to a magnetic flux from a magnetic circuit including the permanent magnet and the magnetic yoke; a signal retrieval member electrically connected to the magnetic element (61, 62); and a unit housing that is formed of resin, houses the permanent magnet and the magnetic yoke, and that is molded integrally with the magnetic element (61, 62) and the signal retrieval member so as to cover the magnetic element and the signal retrieval member; wherein the unit housing includes a body portion provided with an internal space in which the permanent magnet and the magnetic yoke are housed; and a connector portion provided with an internal space in which an end of the signal retrieval member exposed from the resin is disposed, and in the unit housing, a communication path is formed through which the internal space in the body portion is in communication with the internal space in the connector portion, characterized in that said communication path is adapted to allow air to pass from the internal space in the body portion of the unit housing to the internal space in the connector portion of the unit housing through the communication path.