A connector (130) is arranged between an inner support (110) and an outer support (120), and connects the inner support (110) and the outer support (120). A deformable body (140) has one end connected to the inner support (110) at a first position with respect to the direction of rotation about a Z-axis and the other end connected to the outer support (120) at a second position different from the first position, and is bent to be deformed in a radial direction by applying compressive force or tensile force between the first position and the second position. A detection body (150) includes a capacitative element including respective electrodes disposed to face the deformable body (140) and the outer support (120), and detects an elastic deformation generated in the deformable body (140) on the basis of the characteristic value of the capacitative element.