Provided is a high-speed 3D imaging system using continuous-wave THz beam scan, and more particularly, a high-speed 3D imaging system using continuous-wave THz beam scan capable of acquiring a 3D image for a sample at a high speed and high precision by measuring a signal reflected from a sample using the continuous-wave THz beam generated from a wavelength-fixed laser and a wavelength-swept laser and having a frequency varying at a high speed to obtain depth direction information on a sample and performing a 2D scan on the sample using a THz beam scanner.