A novel input device that is highly convenient or reliable is provided. A novel input/output device that is highly convenient or reliable is provided. A semiconductor device is provided. The present inventors have reached an idea of a structure including a plurality of conductive films configured to be capacitively coupled to an approaching object, a driver circuit that selects a conductive film from a plurality of conductive films in a predetermined order, and a sensor circuit having a function of supplying a search signal and a sensing signal.