To provide a ranging device and an automatic focusing camera equipped therewith capable of obtaining exact distance information by performing accurate distance measuring operation even to a mirror surface subject.

In this range-finding device and this automatic focusing camera equipped therewith, a light projecting lens forming a light projecting means for radiating beam light to the subject is provided with a reflection preventing film consisting of a transparent thin film having a smaller refractive index than that of material constituting the light projecting lens at least on its one surface.