The invention allows size reduction of a sensor of a position detecting device of a capacitive system, which detects a position indicated by an indicator. The sensor has plural electrode conductors that are disposed adjacent to each other and are configured to receive a signal from the indicator on a first surface of a substrate having the first surface and a second surface opposed to each other. The position detecting device includes a signal processing circuit including a differential amplifier circuit that calculates a difference between signals from at least two of the plural electrode conductors. Plural connecting lines are formed on the second surface of the substrate. The plural connecting lines each have one end connected to one of the plural electrode conductors disposed on the first surface by a through-hole or a via formed through the substrate, and the other end connected to a line-concentrated part.