A touch panel input device includes a plurality of first electrode lines, a plurality of second electrode lines, a drive circuit, a reception circuit, a touch detector, a ground state switching circuit, and a controller. The controller executes drive control for causing the drive circuit to sequentially input a drive signal to electrode lines in a non-ground state among each of the plurality of first electrode lines, in a state of controlling the ground state switching circuit to set a part of electrode lines among each of the plurality of first electrode lines and/or the plurality of second electrode lines to the non-ground state, and set the other electrode lines to a ground state.