A rangefinder apparatus includes an infrared emitting device (IRED) for projecting a light beam toward a target object; a position sensitive detector (PSD) for detecting light of the light beam reflected from the target object and outputting an output signal corresponding to a distance to the target object; an output circuit for charging an integrating capacitor according to the output signal of the PSD and an analog-to-digital (A/D) converter for converting a voltage of the integrating capacitor after an end of a rangefinding operation including a number of light-projecting actions by the IRED, light-detecting actions by the PSD, and integrating actions by the output circuit are repeated. Multiple rangefinding operations are carried out with a different number of repetitions, and the distance is determined according to respective values obtained by A/D conversions after the rangefinding operations. Consequently, conversion errors in A/D conversions are reduced, whereby the rangefinding accuracy is improved.