An exemplary embodiment provides a method which etches a second layer in a base body to be processed having a first layer containing Ni and Si and a second layer containing Si and N which are exposed to a surface thereof. The method according to the exemplary embodiment includes (a) preparing a base body to be processed in a processing chamber, and (b) supplying a first processing gas which contains carbon and fluorine but does not contain oxygen into the processing chamber and generating plasma in the processing chamber.