A touch panel device including: a substrate; a first sender element for sending surface acoustic wave, which is placed along a first direction on the substrate; a second sender element for sending surface acoustic wave, which is placed along a second direction, orthogonal to the first direction, on the substrate; a receiver element for receiving the surface acoustic wave from the second sender element, which is placed along the second direction on the substrate while facing the second sender element with an interval in between; and a reflector, which is placed on the substrate, for achieving the receiver element's reception of the surface acoustic wave from the first sender element by reflecting the surface acoustic wave from the first sender element, wherein a position of a contact body touching on a contact surface is detected by transmitting the surface acoustic wave that is sent from the sender element through the contact surface and receiving the surface acoustic wave on the receiver element.