To provide a cooling tower capable of uniforming diffusion of circulation water to an upper part of a filler material and to reduce costs by reducing the number of components.

In this cooling tower 1 having an upper water tank 9 provided with a circulation water dropping hole 25 for dropping the circulation water W in a tank to the upper part of the filler material 6 disposed at its lower part, on its bottom plate 20, the bottom plate 20 of the upper water tank 9 is cut and curved to form a circulation water diffusion member 26 for diffusing the circulation water W dropping from the circulation water dropping hole 25, integrally with the bottom plate 20.