The object is to provide a mounting structure for a torque sensor capable of improving a detection accuracy of a torque sensor. A torque sensor includes a first structure, a second structure, a third structure provided between the first structure and the second structure, and at least two sensor units provided between the first structure and the second structure. A plurality of contact portions are provided on one of the first structure and the first attachment portion and one of the second structure and the second attachment portion, and are in contact with another of the first structure and the first attachment portion and another of the second structure and the second attachment portion.