To prevent any detergent or chemicals from remaining in the conveying path, to prevent environmental pollution from being caused and to reduce the cleaning cost by performing the cleaning without using any detergent or chemicals, in a cleaning process of a conveying path for liquid beverage/ food such as milk, which process basically comprises alkali cleaning, acid cleaning and sterilization cleaning.

In the above cleaning process, as cleaning water for the alkali cleaning, electrolytic alkaline water is used and also, as cleaning water for the acid cleaning and sterilization cleaning, electrolytic acidic water containing an active chlorine component is used, to eliminate the need of using any detergent or chemicals.