An input device includes contacts having resistive elements and low-resistance elements opposing the respective resistive elements, an operating unit varying the contact areas between the low-resistance elements and the resistive elements, and detecting means for switching an operation mode of the input device in response to the operation of a supporting leg provided on the operating unit. When the operating unit is not operated, the detecting means switches the operation mode to a sleep mode while the resistive elements and the low-resistance elements are kept in contact with each other. When the operating unit is operated, the detecting means switches the operation mode and the sleep mode is disabled.