A distance measurement system for measuring a distance with a little time difference while maintaining high accuracy. An infrared emitting diode (IRED) emits a beam of light toward an object at a distance to be measured and a position sensitive detector (PSD) receives reflected light. Outputs from the PSD are processed by signal processing circuits, and an arithmetic circuit, which issues an output as distance information. An integrating circuit integrates the signal outputted by the arithmetic circuit and outputs a signal corresponding to the results of the integration. A CPU determines the distance to the object based on the signal outputted from the integrating circuit. In this distance measurement system, the integrating circuit starts integrating the signal outputted from the arithmetic circuit, immediately after the output, i.e., distance signal, from the arithmetic circuit is stabilized.