The present invention provides a new pharmacologic-functioning water demonstrating pharmacologic function without any side effects, and usage of the same. The pharmacologic-functioning water, which demonstrates pharmacologic function without any side effects and includes antioxidant-functioning water as an active principle containing hydrogen-dissolved water, which is made up of molecular hydrogen used as a substrate that is included in raw water, and a precious metal colloid, which is included in the hydrogen-dissolved water and catalyzes the breaking reaction of the molecular hydrogen into a product of atomic hydrogen, is used for preventing and/or treating diseases.