A projection system includes a light emitting apparatus that emits detection light to a detection area for detecting indication positions of indicators, and a projector that detects the indication positions of the indicators in the detection area. The projector includes an imaging portion that captures an image of the detection area, and a position detection portion that detects at least one of an image of light generated by the indicator and an image of the detection light reflected on the indicator from data of a captured image of the imaging portion, and discriminates and detects the indication positions of the indicator and the indicator based on light emission timings of the indicator and the light emitting apparatus.