The bacteriocidal effect of copper sulfate (CS)-electrolyzed acid solution (EAS) that was mixed with up to 6% of organic matter (sterilized cattle slurry) was evaluated. Escherichia coli (ATCC 11775 strain) was killed by the 2.5%×10^-2 CS-EAS, but not by the CS dissolved with tap water or distilled water at the same concentration. Then, the EAS was used as walk-through footbaths for five months to control the clinical lameness with digital dermatitis (DD) in a dairy farm with 130 lactating cows where DD had been endemic. The first washoff bath contained the EAS and the second bath contained the 2.5% CS-EAS. The pH of the second bath increased from 3.1 to 4.5 and COD from 230 to 3890 ppm after each footbathing. The monthly prevalence of clinical lameness with DD was 1.5% to 3.9% during the experimental period and was not different from the previous four months when the 5.0% CS-tap water solution was applied for the footbaths. We consider that the copper sulfate quantity consumed for DD in a herd can be cut in half by using EAS.