Disclosed is a multiple separation filter including a microfiltration membrane, an active carbon-based filter and a ceramic filter stacked in order, wherein the active carbon-based filter is obtained by mixing active carbon with at least one selected from zeolite, gold, silver and a mixture thereof, treating the mixture with plasma gas of 60,000° C. to 70,000° C., and then quenching the mixture to −200° C. to −273° C. under vacuum, and the ceramic filter is obtained by quenching plasma gas generated by heating magnesium at 60,000° C. to 70,000° C. to −200° C. to −273° C. under vacuum. Disclosed also is antioxidant water obtained by using the multiple separation filter. The antioxidant water has a negative oxidation reduction potential.