A signal processing circuit is connected to one of a plurality of conductors of a position detection sensor having a self-capacitance and configured to generate a signal indicative of the self-capacitance for use in correcting a pointer position detection signal. The circuit includes a capacitor circuit and detects a change in capacitance between the conductor and a pointer (e.g., a finger) as a change in voltage in the capacitor circuit. The signal processing circuit further includes: a gate circuit which controls the connection between the capacitor circuit and the conductor; and a voltage supply control circuit which temporarily sets, to a defined voltage level, a first end of the gate circuit to which the conductor is connected and sets a defined potential difference between the first end and another (second) end of the gate circuit to which the capacitor circuit is connected.