Provided is a highly thickening composition which overcomes drawbacks seen in thickening compositions using a polysaccharide in that a desired viscosity cannot be achieved when the thickening composition is added to a liquid composition having a specific salt concentration, and that even when the desired viscosity is achieved, the resultant liquid composition shows deterioration of texture such as remaining in the mouth or being hard to swallow because the resultant liquid composition undergoes little change in viscosity at respective temperatures, and which has a synergistically excellent thickening property. A highly thickening composition produced by mixing one of either (A) xanthan gum or (B) locust bean gum with (C) guar gum and then mixing the component (A) or the component (B) to the resultant mixture, wherein the ratio of the total amount of the components (A) and (B) to the amount of the component (C) is 95:5 to 70:30 by mass and the component (A) is contained in a larger amount than the component (B).
