To provide a low-cost and short-term freezing method for ground around an existing small-sized underground structure, which is excellent in a surrounding environment.

In this freezing method for the ground around the existing small-sized underground structure, the underground structure is equipped with at least a structure body; a cooler, which connects a liquefied gas feed passage connected to a liquefied gas feed unit and a liquefied gas recovery passage connected to a liquefied gas recovery unit, is arranged at a predetermined depth in the structure body; and a ground around the underground structure is frozen by feeding liquefied gas to the cooler and cooling air in the structure body.