There is provided a washing method which imposes a minimized burden on environment, uses a detergent solution significantly safe for human body, and is also capable of safe and hygienic washing and sterilization and prevents effluents from contributing to pollution, eutrophication and the like. An alkaline buffer solution can be used to swell and dissociate stain from an object to be washed and in the solution a component of the stain mainly of an oily component can be floated to effectively wash the object. It is thus no longer necessary to use a surfactant, as conventional. Furthermore, a substance capable of electrolytically producing hypohalogenous acid having a bactericidal effect can be added so as to electrolytically produce hypohalogenous acid in the buffer solution to more effectively wash and sterilize the object to be washed.