To prevent the growth of algae etc. while supplying a liquid chemical efficiently.

This apparatus for supplying the liquid chemical is provided with: a liquid chemical supplying part 4 capable of supplying the liquid chemical to cooling circulation water W; and a supply control part 6 capable of controlling the operation of the liquid chemical supplying part so that the supply of the liquid chemical is started when the intensity of sunshine becomes equal to or higher than a preset intensity and is stopped when the intensity of sunshine becomes lower than the preset intensity.