To provide a method for repairing an upper water tank of a crossflow cooling tower, which allows inexpensive repair while suppressing reduction of cooling performance in repair of the upper water tank of the crossflow cooling tower even when filling material cannot be re-filled due to damage of the filling material or a supporter for the filling material.

When repairing an upper water tank 2 of a crossflow cooling tower 1, a part of a filling material 3 is removed for prevention of fire, pressure loss generating means 10 which generates a pressure loss equivalent to that generated by the removed filling material 3a is provided in a portion from which the removed filling material 3a is removed.