Provided is an apparatus for real-time non-contact non-destructive thickness measurement using a terahertz wave, and more particularly, an apparatus for real-time non-contact non-destructive thickness measurement using a terahertz wave, which is capable of measuring a thickness of a sample by irradiating a terahertz continuous wave, which is generated from a wavelength-fixed laser and a wavelength-swept laser and of which the frequency is changed at a high speed, to the sample and measuring the terahertz wave transmitting or reflected from the sample.