A processing method of subjecting at least two stacked films, which comprise a first film and a second film of a target object to be processed, to a removing process by wet etching comprises bringing a first process liquid into contact with the first film of the target object, thereby etching the first film, determining whether the first film has been removed or not, switching the first process liquid to a second process liquid differing in a condition from the first process liquid when it has been determined that the first film has been removed, and bringing the second process liquid into contact with the second film, thereby etching the second film.