A touch panel device includes a cover panel that has an operation surface and bends corresponding to a depressing force applied to the operation surface; a touch sensor unit including touch sensor electrodes that output touch sensor signals; an elastic member that has a dielectric constant changing corresponding to a temperature and deforms due to the bending of the cover panel, the elastic member including an adhesive agent provided between the cover panel and the touch sensor unit; a first sensor unit that detects a capacitance changing depending on the dielectric constant and a thickness of the elastic member; and processing circuitry to estimate the temperature based on the capacitance detected by the first sensor unit; to detect the depressing force based on the estimated temperature and the capacitance detected by the first sensor unit; and to execute processing of the touch sensor signals based on the detected depressing force.