To provide a laser length measuring device capable of performing effectively highly reliable distance measurement utilizing a self-coupling effect of a laser element.

In this laser length measuring device equipped with the self-coupling type laser element for irradiating a wavelength modulated laser light toward a measuring object, into which the laser light reflected by the measuring object is introduced, a modulated laser light generated by the self-coupling effect of the laser light in the laser element is subjected to frequency analysis to thereby measure the distance to the measuring object. The device is also equipped with a means (a filter circuit comprising a high-pass filter and/or a low-pass filter) for specifying a detection distance domain of the measuring object by restricting a detection range of a frequency component determined by frequency analysis of the modulated laser light.