PURPOSE: To eliminate the environmental pollution, danger to the human body, its expensiveness and decrease in cleaning quality which has not beed attained by the conventional technique by using a detergent harmless to the human body and not causing environmental pollution for cleaning to realize high cleaning quality at a low cost.
CONSTITUTION: When a substrate is decontaminated by cleaning, the fine powder having the same or different composition with respect to the substrate is dispersed in a cleaning soln., ultrasonic cleaning is applied, the substrate is cleaned by injecting the cleaning soln. from a nozzle in the soln. or gas atmosphere, or the soln. is agitated to clean the substrate.