A distance-measuring device, comprising a light source unit for emitting a distance-measuring light, a photodetection optical system, a projecting optical system for projecting the distance-measuring light from the light source unit to an object to be measured and for guiding the distance-measuring light reflected by the object to be measured to the photodetection optical system, and an internal reference optical system for guiding the distance-measuring light from the light source unit toward the photodetection optical system, wherein the light source unit can emit two distance-measuring lights having different spreading angles and having the same or almost the same wavelengths, and the photodetection optical system has an optical filter which transmits light components of narrower wavelength range of the distance-measuring light.