A water soluble bactericide is obtained by ozone-oxidizing glycerin.
Specifically, a 0.1 to 20% glycerin aqueous solution and gas phase ozone
obtained by ozonizing oxygen through contact between oxygen and a silent
discharge field, are brought into gas-liquid contact with each other,
thereby to ozone-oxdize glycerin. Alternatively, a 0.1 to 20% glycerin
aqueous solution is electrolyzed, thereby to produce ozone directly in the
glycerin aqueous solution.