The present invention relates to a composition, containing, as an active ingredient, high-hardness mineral water prepared from salty underground water or deep-sea water, for preventing or alleviating a decrease in blood pressure or symptoms related thereto. According to the present invention, the high-hardness mineral water prepared from salty underground water or deep-sea water, especially, prevents a rapid decrease in blood pressure or mitigates the degree of decrease in blood pressure, during or after exercise, and thus can be used to prevent or alleviate symptoms related to a rapid decrease in blood pressure during or after exercise.
