An optical measuring device including a light source, a light beam path adjuster, a light detector and a controller is provided. The light source may emit light toward an object in a predetermined progress direction. The light beam path adjuster may be disposed between the light source and the object and may change a progress path of the light emitted from the light source. The light detector may receive the light that is reflected from the object after passing through the light beam path adjuster. The controller may compare a first effective beam path length of the reflected light that the light detector receives with a predetermined target beam path length and control a refractive angle of the light beam path adjuster based on a beam path length difference between the first effective beam path length and the predetermined target beam path length.