A position detection system detects a position of an active pen. The position detection system includes: a display device that displays image data by driving each of a plurality of pixel electrodes; and a touch panel including a sensor electrode and a touch sensor. The active pen communicates with the touch sensor using a frequency included in a predetermined frequency band by a charge induced in the sensor electrode. The display device suppresses at least one frequency component included in the predetermined frequency band in capacitive noise that occurs in the sensor electrode due a voltage vibration in an interconnect in the display device caused by driving of the plurality of pixel electrodes. The active pen and the touch sensor communicate by detecting or sending out a signal with a predetermined frequency included in the predetermined frequency band.