A touch sensor device includes: a touch panel on which a capacitance is formed with a pointer; a signal calculation unit calculating a signal output value based on a magnitude of the capacitance; a contact determination unit comparing the signal output value with a threshold and determining whether the pointer has been brought into contact with or separated from the touch panel; and a threshold calculation unit updating a first threshold used for determining whether the pointer has been brought into contact with the touch panel, if an increase of the signal output value is detected during a first unit time within a time period from a determination that the pointer has been brought into contact with the touch panel until a determination that the pointer has been separated from the touch panel.