The present invention relates to a method of extracting a low-molecular-weight proanthocyanidin using cranberries and lactic acid bacteria, and more particularly, the method may include (S1) growing and extracting a seed culture from cranberries, (S2) reinforcing the metabolism of a saccharide by adjusting a metabolic process, (S3) extracting the seed culture whose metabolic process is adjusted and culturing the extracted result, (S4) mixing cranberries, distilled water and a saccharide with the grown seed culture and fermenting the mixture, and (S5) extracting an unbound polyphenol from the fermented mixture.