Abstract: A strain sensor includes a cylindrical strain body extending in an axial direction, a first fixed part, a second fixed part, and a strain detection element. The first fixed part is connected to the strain body at a first connection part and extends from an opening of a first end of the strain body in the axial direction. The second fixed part is connected to the strain body at a second connection part and extends from an opening of a second end of the strain body in a direction opposite to the first fixed part with a gap interposed between the strain body and the second fixed part. The strain detection element is disposed such that a center of the strain detection element is closer to the second fixed part than a center of the gap in the axial direction.

Abstract: A strain sensor is configured to detect a load. The strain sensor includes a deformable section having an annular shape, a first pressure-receiving section configured to receive the load applied thereto, a second pressure-receiving section connected to the deformable section, and a strain detecting element provided on at least one of the first pressure-receiving section and the deformable section. The first pressure-receiving section is connected to the deformable section in a first direction away from the deformable section. The second pressure-receiving section is connected to the deformable section in a second direction opposite to the first direction from the deformable section. The first pressure-receiving section is provided only in the first direction from the deformable section. The strain sensor can stably detect the load regardless of a method for applying the load.