It includes a knob including: an operation portion comprised of a ring-shaped conductive material, a rotational operation being performed on the operation portion; a rotary supporting member comprised of a ring-shaped non-conductive material and fixed onto a capacitive type touch panel, for rotatably supporting the operation portion; a ring-shaped concave groove disposed in the rotary supporting member; and a conductive conducting terminal portion electrically connected to the operation portion and rotating inside the concave groove integrally with the operation portion, the position of the conducting terminal portion being detected by the touch panel, wherein the conducting terminal portion is comprised of a plurality of conducting terminal portions, surfaces of the conducting terminal portions being in contact with the concave groove, at least two of the surfaces of the conducting terminal portions being different in contact area from each other.