An input device includes an input circuit including a plurality of key switches connected in parallel to one another, and a control circuit including a key input terminal to which a first terminal of the input circuit is connected, and an interrupt terminal to which a second terminal of the input circuit is connected. When a key switch is turned ON, an interrupt signal is input from the second terminal of the input circuit to the interrupt terminal, whereby the control circuit transitions from a power saving mode to a normal mode. Then, the control circuit determines which one of the key switches is turned ON based on a value of a voltage applied from the first terminal of the input circuit to the key input terminal. Thus, it is possible to realize a power saving mode without having to provide a comparator.