Abstract: An operation knob apparatus includes a base a conductive transmitting member, an operation member that brings the transmitting member near to and away from a display panel, and a stabilizer disposed between the bases and the operation member. The stabilizer includes a main body, a pair of arms connected to respective ends of the main body, and a pair of base portions and connected to the respective arms. One of the base and the operation member has a holding portion configured to rotatably hold the main body, and the other has a pair of holding grooves respectively configured to slidably and rotatably hold the base portions.